Yeah I just noticed that and was all wtf when did that happen,Sam always has that trait, so she didn't "get" it somehow. However, despite its name it doesn't mean she cannot conceive, just that her chances are lower than with other girls.
There certainly will be a console command to remove it but (a) they tend to kill your save, and (b) since it is a "hard coded" attribute, it may not be saved, so you'd have to do it all over again with each new start. This may be wrong though, I didn't look into the code.
Had banged her several times waiting for the success notification (egg and sperm cell pop up),
Then noticed she had that trait and had 0% fertility,
I was looking everywhere for a fix but then I noticed sam was getting plump,
She got pregnant without the success notification ever popping.