Genes for sure. Wouldn't it be nice to be able to have a "gene cleanse" and get rid of all the unwanted issues? Not before birth - just after you have had enough experience living with them that you decide - enough is enough.
Though, I wonder what it would be like to be 6 inches taller suddenly ... I guess I would need a bigger penis to balance me too.
Haha, yeah I could think of quite a few things that I would change gene wise.