How are the last names of kids determined? I had Beau Merrick impregnate each of his three roommates and the kids they had all shared last names with their mothers. Is this always the case, kids taking after their mother?

Kids will always have their mother's last name. So if the mom isn't married to the kid's father, they won't have their dad's last name. I usually just change the kids' last names in City Hall when that happens, though. But not always. It's realistic to have it both ways, actually. Like my son (IRL) has my last name, but I have a friend whose kid has her kid's father's last name, even though they're not married.