More like this

I was just curious as to how this function works?
In my latest story "Becoming Holly" the "more like this" included the twist endings "Instrument", "Making a Scene" and "Rehabilitation" and a couple of others "Closer Friends" and "Sought After".
It possibly should have included "Uncle", "Bait", "The Surgeon" or the multiple personality one - forgot the name!
Is it an algorithm?
Maryanne