Teen sims can have crushes on (half)siblings who was taken by social services?

Hello! I wasn't sure where to put this, as it doesn't feel like a bug in the way the stuff on the bugs forum are. It feels more like an oversight. I do think this should be fixed, though.

I noticed that this was possible because one of my sims invited her half-brother over from school, and then a want showed up about her crush with said brother's icon.

I assume this is an issue with sims getting adopted and how their biological parents are organised within the family tree, but this is quite disturbing if you are keeping track of your sims' stories. 

I understand that this is an incredibly niche issue so it is probably not important, and I don't know if the issue is even fixable, but it would be nice if it could be fixed.

Thank you for reading!