Descendants not Vampires?

[MoirailZoned]

Hi. So, I started out my game with 2 sims; Vampire father and human daughter. It's been a while and at this time the daughter has been a vampire for, maybe a sim year and a half? I go back and fourth between the future and present very often. My descendants were human to begin with, because the first time we visited, the girl was still human. However, they've never gone vampire? I thought they were supposed to, so this is puzzling to me. They've had all other changes; wealth, location, etc. The descendants themselves just haven't changed at all.