So, here's an intersting blog entry.
This game designer is talking about a game he's been working on where you follow a tribe of people through several generations as they attempt to surive a migration to their new home. Since the character would have individual names and the younger kids would grow up and, eventually marry and have kids of their own, the designers how he's trying to develop an "anti-incest" algorithm so that the characters AI doesn't cause to commit incest.
It's actually an interesting post.
You can read about it here.
http://www.fortressofdoors.com/2011/09/designing-anti-incest-algorithm.html