I've said it before but I'm pretty sure you're right. I'm pretty certain he has a daughter. And no I'm not going to post any evidence.
Also, it doesn't matter anyway. Encouraging people to have babies is a good, positive message whether you have kids or not. A lot of people say sam's a hypocrite when he gives advice that goes against his own personal life decisions, but that doesn't make someone a hypocrite. It means they learn from their mistakes, like a drug addict telling kids to not use drugs, or a RISD graduate telling people art school is a waste of time and money.