I have the mod that changes the duration and the teen pregnancy thing. I always shuffle families, and when I came back to my main to name the baby when it was born, it showed up in the family tree as half-brother to his sister and stuff like that. He was only related to his mum.

I did the "Try for Baby" by myself and have the Awesome mod, so it couldn't have been parthenogenesis...? Help? I just lost hours of progress because of that. I'm sort of obsessive-compulsive. ^^"

(And the username's my little brother's. I forgot the password to mine.)

Same exact thing happened to me! I don't know what it is either.

I read in another post that if you move your sim while preg the baby won't be related to the Dad. I haven't had it happen because I didn't want to take a chance after reading that so I have never moved any of mine.