Do they train? Will they fight? Will they play soccer?
Surely he's mentioned this in one of his pre-fight specials.
I remember him saying he didn't want his sons to fight or something to the effect of that...
Shit. I wonder if his wife is good breeding stock. Maybe they'll be badass soccer players.
Kid at school:”My dad can beat up you dad”
Andy's kids:”Really? keep thinking that”
All I know is they're already pretty big and they look just like him. With those kind of genes it'd be hard not to excel at almost any sport they put their heart in. 
Now that MMA has been around for 18 or so years, we should start seeing the kids MMA legends rising up the ranks. I think Randy Couture's kid might have been the first to take up dad's profession... other than the Gracie kids, of course.