I'm pretty sure the best age to start having children is 0, also known as the moment of conception.
This way, you don't have the retraining/deprogramming problems you get when you start out with an older child.
It's like dogs – you think getting them after their already housetrained is a good thing, but you wind up spending a lot more time just creating a strong parent-puppy bond than you otherwise would have, and you'll still need to learn how to parent "in situ", without the advantages of starting to do so with a youngling that cannot just run away.
deano.com 