I wouldn't count on it. Even if it were possible the genetic pool is too vast for single traits to really have an impact. Plus consider that most (if not all?) homosexuals have heterosexual parents - that is more influenced by number children, but it shows that there is more involved than just people who have the traits being selected out. Most of the biggest advocates against religion were born in religious families. Most parents regret having kids, most couples who have kids are less happy than couples who don't have kids. People wanting to be child free is here to stay and it will grow before it has any chance of being bred out. Choosing to be child free is the rational thing to do if you want to be happy. I welcome people to join more people avoiding having kids here: http://reddit.com/r/childfree