If you had a child who had an untreatable genetic illness, how much would you tell it? What if you knew the future contained heartache and pain for both you and the child?

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Disclaimer: The original characters and plot of this story are the property of the author. No infringement of pre-existing copyright is intended. This story is copyright (c) 2009 Penny Lane. All rights reserved.

*****

"My Mummy isn't going to come back, is she, Daddy?"

"No, Luke. I don't think you'll ever see your mother again."

"You said before she was pretty. Was she very pretty, Daddy?"

A pause. "Yes, son, she was very pretty."

*****

"Dad, the others at school keep saying I'm a freak, because I heal up much quicker than them. I'm not a freak, am I?"

"Of course not, you're perfectly normal."

"Well, why do my cuts and bruises get better much quicker than everyone else's? Other people have to keep plasters and bandages on much longer than I do."

"I don't know, Luke. Perhaps it's because you're naturally much healthier than most of them to start with. You eat well, and you don't get any of the childhood diseases like the others do. You're just lucky."

"If you say so, Dad. It just seems a bit weird, that's all."

"Don't worry about it. Worry instead about your homework. Have you done that Geography assignment yet?"

"Aw, Dad..."

*****

"Thank you for seeing me, Mr. Allendale, Matron. I am delighted that you have accepted Luke into St. Joseph's, but I thought that I should come and inform you, like any good parent, of one or two things you need to know about him. Things that couldn't be put on the application forms."

"Have a seat, Mr Renshaw. What's this all about?"

"Thank you, Mr Allendale. I assure you it's nothing that should worry you, quite the opposite, in fact. Luke suffers from an inherited genetic disease called Baxter-Hildegren Syndrome. Not much is known about it, except the symptoms, and what will happen to him eventually as the disease progresses. I think there are five or six known cases in the entire world, so it's very rare, in fact not even identified until a few years ago."

"But, Mr. Renshaw, there was a space on the form for ailments and disabilities. We have several pupils here with diabetes, for example, it shouldn't have been a problem for you to write it down."

"I didn't want to worry you, as he should be perfectly normal for the entire duration of his education here, and it's a very rare disease. Actually, he'll be more than normal in certain respects. Matron?"

"Yes, Mr Renshaw?"

"The boys here do get the usual run of things passing through, don't they? Coughs, colds, flu, etcetera?"

"Yes, of course. If they are thought to be infectious, we have a ward where we keep them until they improve, and to keep them away from everyone else, of course."

"Luke won't get any of those. He's blessed with an unusually efficient immune system. He's been tested, and it's practically impossible to give him any bacterial disease or virus. You'll also notice that any injuries heal up much faster than usual. That's one of the points you need to make a note of."

"How so, Mr Renshaw? I would have thought that something that gets a boy back to normal as soon as possible is to be preferred."

"Maybe. But consider, if he breaks a bone in his arm or leg, or, well, anywhere, actually. The healing process begins very rapidly, and if the bone isn't set as soon as possible, it may heal at an angle, leaving him with a deformity."

"Oh! I hadn't thought of that. You're right, Mr Renshaw, I'll make sure something gets put on his notes."

"He'll also never need any dental treatment, for the same reason. If a tooth falls out, or gets knocked out, a new one will grow to replace it. Never has cavities either. I wish my teeth were like that."

"Just what happens," Mr Allendale asked, "with this disease, then? Your boy sounds absurdly healthy to me."

"He will be, up to about the age of twenty-five. Somewhere about that age, his body undergoes some serious and life-threatening changes, and he'll end up a completely different person. From that time, he'll require constant care and attention."

"I'm sorry to hear that. How long will he live for, after that happens?"

"Tricky to say. He's not immune to accidents, like any of us. He might live two years, or he might live for fifty. There's so few known cases it's difficult to know for certain what might make a difference to lifespan."

"Oh. I can assure you, Mr Renshaw, that we'll try to make your son's time here as happy and fulfilling as possible. Does he know about himself?"

"The disease? No, not really. He knows the name, and that he heals quickly, but that's all. He doesn't know what's going to happen to him in his mid-twenties, and at this age I would prefer it if he didn't. I would like you to just treat him exactly like any of your other pupils and forget about his future. Other pupils may notice the quick healing, the kids at his previous school did. You will just have to temporise if someone asks questions. The only time you'll really need to be aware of his differences, shall we say, is if he breaks something."

"I'm glad you informed us, Mr Renshaw. It's a shame, though, to teach a boy everything he needs to know about the world, and know that he might not be able to put most of it to good use."

"Maybe, maybe not. Medical science is improving all the time, who can say what the future will hold?"

"So true. Well, thank you for coming, Mr Renshaw. And, a belated thank you for your generous donation to the school funds. I'll get someone to show you out."

*****

"Wait, did you say that some of the boys are going out with girls from St Catherine's?"

"Yes, Dad. What's wrong with that? It's not as if we're children any more. Mr Allendale says that boys over sixteen are allowed out at weekends, and that we're allowed to mix. We've all had the birds and the bees lecture in biology, so we know how far we are allowed to go."

"Yes, Luke, and under normal circumstances I would have no problem with that. However, as you very well know, the circumstances are not normal. You have a very rare genetic disease, and, although you won't pass it on to any girl you make out with, if you make any mistakes," and they both knew what he was talking about, "you might be condemning any child you end up with to a life of misery."

"Misery? How so, Dad? My life hasn't been miserable so far, in fact it's been jolly good. Dad? What haven't you told me?"

Daniel Renshaw sighed. Time for the next dribble of information.

"Sit down, Luke. There are things you ought to know."

"Dad? Now you're worrying me."

Daniel paused while he tried to find a way to tell his son his fate.

"Luke, I didn't want to upset you as you were growing up, but as you're now sixteen it's probably about time I told you a little bit more about what's wrong with you."

"Wrong with me, Dad? I don't feel as if there's something wrong with me."

"That's because you're still young. When your body gets to about the age of twenty-five, it will all change, though. The disease you have will cause you to undergo some serious bodily changes, and your whole life will change completely."

"What? You mean I've got," Luke counted up, "nine years left to live?"

"I didn't say you'd die then. And it can happen any time from about twenty-two years of age to twenty-eight or so, although twenty-five is usual. You just have to be aware that any plans you make that go beyond about your twenty-fifth birthday might be a waste of time."

"Well, what happens to me afterwards? Am I some kind of vegetable, then?"

"No, not at all. You could live a long and fulfilling life, or you could have just one or two years left. It just won't be the sort of life you might have been expecting."

"Oh." Luke was silent while he tried to assimilate the bombshell his father had given him. So much for becoming an airline pilot, or a famous sportsman, or a rich banker, then. "How do you know this, then? And if this disease is genetic, why didn't you get it? You're obviously older than twenty-five."

"I know about it because there's an Institute which specialises in such things. Your mother got into contact with it as soon as the condition was discovered. And it's known that your mother carried the Syndrome. The only part your father played in the process was to make you a boy not a girl."

"Oh. Biology again. I understand." Luke thought again. "Is that why Mother died, then? Because she was carrying this disease?"

"No, she was killed in an accident. There are side effects which a woman can get, but it hits males the hardest. She was killed before any effects happened to her."

"I'm sorry, Dad. I know you loved her very much, didn't you?"

Daniel Renshaw was silent for a long time. Then, he said, "Yes, Luke, she was my whole life."

*****

"Thank you for fetching me, Dad," Luke said as his father's car drove away from the school for the last time, "I might have managed it on the train, but I have all these books and my other stuff to carry."

"No problem at all, son," his father said. "I was quite happy to come to the presentation ceremony in any case. I was surprised, your grades were much better than I'd thought they'd be."

"Where are we going? Home?"

"Yes, to dump all your school stuff and to allow us both to change. Or did you want to go out for a celebration meal wearing your school uniform?"

"Ah, no, Dad, I don't think so. Although I've worn it for seven years, eight years, now, I think I'm quite happy to put it away in my wardrobe and forget it. Where are we going, then?"

"I thought Giordino's in town. This time, you can legally have wine with your meal, if you like."

"Gee, Dad, thanks. And now we've got that out of the way, will you finally tell me what's going on? What's really going on, that is?"

"I have no idea -"

"Don't give me that, I'm not a child any longer. Do you think I wouldn't notice that I was the only boy in my year not to get asked to see the careers master? The only boy not to get asked which University I was going to try for? Despite the fact my grades are so good I could choose from the top tier if I wanted to?"

"I thought we'd talk about it over the meal tonight. I don't want to ruin your leaving day, at least, not too much." Daniel Renshaw changed the subject, or at least seemed to. "Noticed any good girls while you were at that school? You must have cast your eye over those from St Catherine's, at the very least."

"Yeah, one or two."

"Any you were really fond of? That you might want to take things further with?"

"There was this one girl I quite liked. Melanie - Why are you asking me this? You know very well I'm going to turn into a pumpkin in seven years time, so I've been deliberately not getting too involved. I wouldn't want to do anything cruel to a girl I liked that much."

Daniel closed his eyes in memory, and then remembered that he was driving.

"You can do quite a lot in seven years," he said. "If you married someone now, you could have eight or nine children by the time you had to stop. That is, if they were single children one after the other."

"You can't be serious! That would be to treat my, hmm, wife I suppose, as a production line. And it would be irresponsible to leave her with all those kids and no means of support. I wouldn't do that to anyone."

"Perhaps, But I'm just pointing out that you don't have to be a monk for the next few years. You're a young man, you're entitled to enjoy yourself a bit."

"What about all this damage I might do the next generation, then? You were quite hot about it last time you came, now you seem to want me to do the opposite."

Daniel Renshaw sighed. "Yes, that's still true. I'm sorry, Luke, I'm not explaining this right. Will you let me concentrate on driving, and leave this to tonight? I'll answer a lot of your questions tonight, let's just make sure we get home safely first."

"Mmm! I always liked the Tiramisu they did here. I don't suppose you'd let me have any more, though, would you?"

"I don't think so, Luke! You must have put ten thousand calories away tonight."

"Well, you know me, growing boy. Although I suppose I've stopped doing all the sports I used to at school now, so I'll have to taper down a bit."

The waiter put large coffees in front of them and left.

"Now, you know I've been bursting at the seams all evening. Dad, what's going on?"

"First of all, if you still want to go to University, I won't stand in your way. Your good grades were a little unexpected. If you'd had average grades, like everyone expected, then there wouldn't have been a lot of point you going to Uni. The only thing you have to remember is that it would be four years less left to you, although it would be a good four years. University life was one of the best periods of my life, and I don't see that your experiences would be that much worse."

"Uh, okay, but that still doesn't answer the basic question."

"It's part of the answer, which is that you have to choose carefully what you do with the rest of the time remaining to you. Now, we're sufficiently well off, as you know, enough that you don't have to find a job to cover your time left. Nevertheless, I think the experiences would be good for you, and I wouldn't stand in your way if you did decide to find some kind of employment, at whatever level suits you."

"Yes, I see. Then, would you be too upset if I said I wanted to go backpacking round the world for a couple of years? My natural immunity would ensure I didn't get too much trouble with foreign bugs, and I think I'm fit enough to look after myself."

Daniel pursed his lips. "I think I'll have to consider that one in more detail. Now. A factor you might want to bear in mind, is that neither of us has so far mentioned what happens to you after you 'turn into a pumpkin', as you so aptly put it."

"Yes, that's certainly one of the things I wanted to ask you about. I tried to do some research the last few weeks at school, but there wasn't anything to find. Is it so terrible that it's best I don't know what happens? Or can you tell me, so I can prepare myself for it?"

"I can tell you, but the best way to handle this, and it's something I've already set up, is to take you to the experts. Do you remember me talking about an institute some time ago?"

"Yes, but you never said which institute. Was that deliberate? There seems to be so much secrecy about this whole thing. Some of the guys at school wondered if I might be a vampire, but I didn't have a problem with garlic, crosses or silver. Then they thought I was a werewolf, but nothing happened at full moon. I've got obvious brains, so I can't be a zombie. Some of them still think I'm an alien."

A waiter brought the bill on a little dish and placed it by Daniel. He waited until the man walked out of earshot, and then leaned towards Luke.

"This all has to be kept as secret as possible, which is why I've been careful to ensure you couldn't give yourself away, even accidentally, at school. So far as they were concerned, you're just a boy with a strange disease whose life is going to take a nosedive in a few years. Like, say, Cystic Fibrosis. The truth is much, much stranger, and if people find out you could be hunted down and either killed, or kept in a cage like a lab animal."

"Jesus, Dad!" Several diners raised their heads and looked at the Renshaw's table. Luke lowered his voice. "Is it really that bad? You're not just making this up to keep me quiet?"

"Yes, it is that bad, and no, I'm not just making it up. Look, the day after tomorrow, we're going to drive over to the Institute and they'll explain the whole thing to you. If you don't object, I imagine they'll also want to run through some tests on you. And, I might add, they'll probably want to see you back on a regular basis so they can keep a check on your condition."

Luke shrugged. "If this whole thing is real, and it's really going to happen to me, then I don't see that I can object to any of that."

"Okay, then. I suggest you just spend tomorrow chilling out and sorting your school things out and putting them away somewhere. We'll need an early start on Friday."

"I'm a teenager, chilling is what I do. What about, what you were talking about in the car?"

"What was that, then?"

"About girls, and getting married. Or did I misunderstand that?"

"No, I think what I meant to say was, that getting married and starting a family would be a positive use of your remaining time, even if you think you'd not be treating your girl very well. It's an option, just the same as going to University is. You might even manage both."

"What about this genetic business, then? Surely I'm not good material to be a father?"

Daniel looked at his son as they rose from the table. "That will be explained on Friday, and you can judge then for yourself what legacy you might be handing down to your children. Oh, and no, you're not an alien."

*****

"Welcome to the Moebius Institute. My name is Frances Canning, and I am the current head of the Institute. Please be seated. I guess you must be Luke, that Daniel has told us so much about."

"Yes, Mrs. Canning." Luke licked his lips and looked around. On their way in, he had seen a typical research campus in a rural setting surrounded by razor wire. Inside, it was all bright lights and bustling women in white coats.

"Call me Frances, please. I won't bite, I assure you." The speaker was a woman who might have been in her thirties, short light brown hair, dark business jacket and skirt over a pastel top. She looked like somebody's mother.

"Okay, then." Luke licked his lips again, and then said, "Dad says you'll explain what's wrong with me."

"I don't know that I'll do that personally. I've asked one of our senior scientists to come and talk to you, she's been detained a few minutes. Can I get both of you a drink while you're waiting? I have a few questions I'd like to ask Daniel, if that's all right with you, Luke."

Drinks were ordered, and while they waited Frances asked Daniel about all kinds of things, his health, his job, where he lived, even about the investments Daniel had made which kept their household solvent and affluent. Luke listened with one ear and wondered why the Institute was so interested in his father's life.

While they were drinking, a new woman appeared. She was blonde, about the same age as Frances and wearing a white lab coat. The two men stood up.

"This is Doctor Alice O'Toole. Luke, she'll be looking after your interests from now on." Daniel and Luke shook hands with the newcomer.

"What happened to Doctor Margaret, Frances?" Daniel asked.

"Oh, she had a son about eighteen months ago."

"I'm sorry to hear that. I mean, I'm sorry you've lost such a good member of staff."

"If you'll come next door, we have a projector set up. You might as well bring your drinks, and the tray."

"Now, Luke," began Alice. "The rest of us here know all of what I am about to tell you, so this lecture is entirely for your benefit, although there may be new developments which Daniel has yet to be told about. Stop me if you need something explained, please do."

Alice went to the projector, started it, and displayed the first slide.

"You presumably have done some genetics at school?"

"Yes, er, Doctor Alice. That on the chart looks familiar to me, it's the standard explanation of Mendelian genetics. We did that in biology." He screwed up his face. "I hope this isn't going to get too deep, because I've only just left school, I haven't done this to University level."

"No, that's all right, you'll understand what we have to tell you. How about this next one." Alice displayed the next slide, with diagrams of chromosomes on it.

"Ah, yes. That's the human genome, I think they call it now. Twenty-three pairs of chromosomes, is that right?"

"Yes, that's right. Now, most of those are very similar looking except the last one. Know why that is?"

"Yes, it's because one of each pair of chromosomes comes from each parent. The last one is different because that's the one that determines sex."

"We tend to say gender here, rather than sex. But you're right in your explanation. Do you know how the choice of gender works?"

"Yes, the woman has XX and the man has XY. Each egg has one of the two X's in it, together with one half of each of the other chromosomes. The man's sperm has XY, and sperms get X or Y. If the fertilised egg gets an X, it's a girl. If it gets a Y, it becomes a boy."

"Right. And do you know how to tell a Y on this chart?"

"It's the little stubby one. My biology teacher said that it's just a switch, which turns on the male genes in the body."

"Very well. Now, the real point of the discussion we are having today, is to tell you that you do not have a Y chromosome."

"Come again? Do you mean I'm a girl?"

Alice sighed. "It's a lot more complicated than that, unfortunately. What you have instead is a chromosome that is not the X chromosome, that is nearly as big as the X chromosome, but instead of just one switch, it's completely packed with switches."

Luke sat, trying to digest what he had been told, but all his life he had been told he had a genetic abnormality, so this news was mostly just confirmation. He considered what he had been told.

"So, I guess that one of the switches on this big thing is the male switch, which is why I look like I do, and why I have a penis and testicles. And, I guess, what you're saying is that at about the age of twenty-five, some of these other switches kick in, and do something horrible to me."

"I wouldn't use the word horrible, exactly," Alice said, "but otherwise, you've figured it out mostly right. We call this 'big thing', as you termed it, the Z chromosome, although that's only a term we use amongst ourselves, you understand."

She leaned towards him for emphasis. "The thing is, this mutation, for that is what it is, is carried by -" here she halted while she considered her words carefully, "both males and females. Except that they're not males or females, but the same thing."

"You mean, I'm a," here Luke had to dredge the word out of the depths of his memory, "a hermaphrodite?" He ended with a query in his tone.

"No, not one of those. They have both sets of genitals at the same time. With this mutation, you can only be one or the other at any one time."

"Ah, so what you mean is, that I'm -" Luke stopped.

"Yes. At about the age of twenty-five, you're going to change into a woman. A complete, biological, fully-functional woman."

Luke's father and the two women looked at him while he digested this. Finally, Luke shrugged his shoulders.

"That doesn't sound so bad. I was afraid I'd be some monstrous shape stuck in a bed in a home somewhere. It'll probably take me a good while to adapt, I suppose, but being turned into a woman isn't the end of the world, is it?" He turned to Daniel. "Is that why you wanted me to get married and have kids? So that I can have the male experiences before they're lost forever?"

His father grimaced. "Yes and no. The situation is a lot more complicated than that. Tell him, Alice."

She resumed. "You will become fully female, with all that that implies. Your face will change, you will grow breasts, your penis and testicles will disappear and you will acquire a vagina and the womb to go with it. Your hips will widen and your skin will soften. Your brain processes will also change. This all takes about six to eight months to happen. Once you have transitioned, you will be a fully female member of society, and you won't feel like something you're not, with one exception. That's the fact that you won't have had twenty-five years of growing up from childhood to become accustomed to your new status in society. You'll have to learn that quickly, and secretly, over the short period after you transition."

"That doesn't sound too bad. What's the big problem, then? I was a man, then I become a woman. I think I can live with that."

"A couple of things. Firstly, being a woman, you are likely to meet a man, get married and want to have children. In Z-females, as we refer to them, the urge to have children is particularly strong. Any daughters you may have will be perfectly normal human girls, with no genetic abnormalities. Half the sons you bear will have your Z chromosome, and will end up like you."

"I see. That's why you showed me those genetics charts. Girls good, boys bad. Well, maybe not bad, just not so good."

"The other major problem in all this is that you are likely to have only one son, unless you have twin boys. You see, a male foetus in it's mother's womb is surrounded by her female hormones, so has to pump out it's own male hormones to ensure it develops properly. In you, the male hormones from your son will trigger off another change in you, and you will turn back into a male again."

"Oh! I understand. What you are saying is that I will flip from being male to female and back again."

"That's exactly what I am saying. You will become male again. The problem is, you will stay that way for twenty-five years, at which point you will change back to a woman once more."

"Oh, God, no! Really? I can see how that might get difficult."

"Child, you have no idea. Imagine, first, you are a happily married woman, with perhaps two daughters already. You then have a son, who is going to be your husband's pride and joy. How is your family going to deal with the fact that you immediately start changing from his loving wife into a man before his very eyes? If you were breastfeeding, you keep the breasts until you wean your son, which will make you look very strange indeed. Then, you also know that your son could be the same as you, and that he might never be the heir that your husband needs. What do you do?"

"Dunno. I hadn't got as far as thinking about the effect on people other than myself."

"You run. You take your son and you run. You have no choice other than to abandon your family forever, no matter how much you loved them and wanted to stay with them. There is no other way, unless you want to be discovered. And being discovered is, for you, a Very Bad Thing."

"I don't see that. It's just a mutation, isn't it? There are plenty of other mutations."

"Consider your own childhood. You already know that you heal faster, that you don't pick up germs or viruses, you don't need dental work. It hasn't happened to you, but I can tell you that your healing abilities include being able to regrow amputated limbs. Eyes, and some internal organs, too. Think what any government would pay to have someone like you locked away in a research establishment somewhere. If they can find out what makes you tick, or, failing that, to force you and people like you with any means at their disposal to do their wishes, they would be able to create an unbeatable army."

Spelled out like that, Luke suddenly understood what his father had been driving at in their restaurant conversation. He was, through no fault of his own, one of a very small group of people who would be hunted down by anyone who discovered their secret.

"There's another thing I haven't told you yet," Alice continued, "about the transition from male to female. When it happens, your body clock gets reset to the age it was when you had your first transition. In other words, you become a twenty-five year old woman again. This doesn't happen when you go from female to male, you just carry on from the age you were when you had your son. You will physically age very slowly compared to normal humans, in either form, which means that if you last out long enough someone might notice and you'd have to move on again. Put the slow ageing together with the age reset when you become a Z-female and, barring accidents, you are potentially immortal."

"Oh, wow. Just wow." Luke was flabbergasted. "I think I need another drink, please. This is amazing. You've just told me I'm one of a group of secret superhumans."

Alice wrinkled her nose. "No, not superhuman, not really. A better word might be 'robust'. You can be killed, and there are certain serious injuries you won't recover from." Her face became grimmer. "I suspect a fair few Z-females got burnt as witches in the past. Some of the men, too. Wars and disease outbreaks are handy, because you can use the confusion to switch identities and move somewhere else. There are some celebrated cases through history that we know are probably Z-humans. There was a person called Chevalier Eon de Beaumont who probably was. There's anecdotal evidence that one of the wives of Henry the Eighth was, as well, although having your head chopped off would certainly qualify as a fatal injury. It's possible Henry's son Edward the Fourth was a Z-male, although he didn't live long enough to transition. There have also been questions over Elizabeth the First, although she's more debatable. However, it seems she was quite determined not to have children, and if she was a Z-woman I can quite understand why. Some Z-women almost certainly perished during the French Revolution, and in other purges throughout the ages when anyone odd was considered suspect. Witches of Salem? Possible."

"Ouch. You'd certainly want to avoid drawing attention to yourself, wouldn't you?" Luke thought. "So, let me get this straight. If you're a male, you can't be one longer than twenty-five years, is that right?" The two women nodded. "If you're female, however, you stay as one up and until you have a son. Is it possible, therefore, for the woman to put off changing by not having children? That way, you could at least choose your moment to change in."

Frances said, "Yes, it certainly is. I can tell you, however, that the urge to reproduce is very strong and resisting it is extremely uncomfortable." She handed him a refill of the coffee, and he looked up at her to thank her. He paused, looking at her more carefully.

"You're a Z-woman, aren't you?"

She nodded, and looked at him expectantly. He suddenly had a thought, and turned to Alice.

"You're one, too, aren't you?"

"I am, although not as old as Frances is. I've been a woman fifty-five years."

"I've been one for eighty," supplied the apparently thirty-five year old woman.

Luke suddenly had an appalled thought, and turned to Daniel, who nodded.

"Me too, although I could have been a normal. Sorry, Luke."

"Are you as old as them, Dad? You look about forty, but if you age slowly -"

"I'm a hundred and nine," replied his father. "I've been a man three times and a woman twice, once for thirty years."

"How many of us are there?" Luke asked weakly, realising that 'us' was now appropriate to the conversation.

"We have no idea," replied Frances. "Naturally, with such an explosive secret, no-one is going to leak out any information if they can possibly avoid it. Nearly all of those who work in this part of the compound are, and the few that aren't Z-people know about us, and are all sons and daughters of Z-people."

"Sons? I thought that wasn't possible?"

To answer that Alice displayed a third slide which was divided into four parts. This showed the possible results of couplings, the first being that of normal with normal, then normal female with Z-male, normal male with Z-female, and finally Z-male with Z-female.

"Oh, yes, of course. It's possible to have normal sons half the time with a normal father and a Z mother."

"Yes, all other male children being Z-males," Alice explained. "The problem with having possible normal sons, is that the mother doesn't know whether to take her son with her when she leaves, before she starts to change. If her son is normal, it might be dangerous for her to take him."

"Yes, I can see that," said Luke. "Ah!" he exclaimed, pointing to the chart. "Something I'd noticed before now makes sense. I'd wondered why this outfit was called the Moebius Institute." He pointed to the logo on the corner of the chart, which showed a Moebius strip, a loop with a single twist in it.

"Clever lad," said his father. "I hadn't noticed the significance before."

"Of course!" Luke said, "The two sides represent the two genders, but it's only one side really, so they are the same thing. The loop goes on for ever, which represents the long potential life we have, but you have to experience both sides of the loop for it to work."

Frances said, "You're pretty smart, you know that? I think we might be able to offer you something useful to do here at the Institute, if you're interested. To continue with your question, we have to do some extreme digging to find people like ourselves, because we have to hide so well. We use, and run, private detectives. We have people in government agencies looking out for certain changes of status, and certain events, like mothers and sons disappearing or dying, or fathers and sons. Medical records are useful sometimes - as are battlefield records. Our historical team sifts through reports of miracles, and suchlike stuff. We have contacts all over the world. We do know that some groups of Romany travellers consist of Z-people, whom they call the 'Daughters of Time', which I consider a very good name for us. Because they move around all the time, and they're not properly recorded anywhere, it's easy to disguise just who and what they are."

Luke sipped at his coffee and tried to make sense of all that he'd been told. From having what he'd thought was a fatal illness, or to all intents and purposes an illness that was going to end his useful life, he had now been propelled into a secret society composed of strange super (he couldn't avoid that word) humans who had the potential to live for ever, and who could be either male or female. It was a lot for an eighteen year old teenager to think about.

"But, but, wait a minute, Dad!" Luke said. "You told me when I was younger that Mother had died in an accident. Was that true, or did you make it up to hide the fact you were a Z-person?"

Daniel sighed. Time to give Luke the final piece of the puzzle. How would he react?

"No, Luke, your Mother didn't die. I had to tell you that so that you wouldn't get asked awkward questions in school."

"Well what happened to her, then? Did she run away when she had me?"

"Yes, she did run away when she had you." Daniel Renshaw suddenly began to feel all of his years. Perhaps, as the world developed and progressed, a time would come when the running away would be unnecessary. But he knew that time wouldn't be for many decades yet. "Haven't you yet realised what we've been trying to tell you? Luke, I am your mother."