Semi-Identical Boy/Girl Twins.

There might be a story idea here. Semi-identical twins, an apparent rarity, share three-quarters of their DNA, vs. 100% for fully-identical twins, or 50% for fraternal twins. While identical twins always have the same birth-gender, semi-identical twins can be a boy/girl pair.
Are these twins more likely to be trans? Intersex? Have a special psychic connection?

Congratulations, It’s Twins. The Doctor Is Perplexed.