Eh, I perfer Stephen Hawkins take on it.
Science doesn't prove their isn't a god. Science just proves that if their is a god he doesn't work in an arbitrary way.
The mating impulse is a physical one, not a mental one. In other words people want to have sex more then they want to have kids. Since having kids is how well the human race continues to exist there is some influence socially to convince people to have kids hence why people have them. (among other reasons.)
In poorer countires the birthrates are much higher because kids help your chance of surviving, once they're out of diapers they're like free labor that you can depend on to help you get through. That's why they have way more kids well that and the mortality rate.
In modern societies kids actually hurt surviviability because they cost a lot of money, well except the people who have kids for the welfare.
