To get a baby, do the following...

1. Be a Male-reason-if you are a Female and you're pregnant you can't work hard as you used to while having a kid inside.
2. Get Married
3. Buy Crib for baby. Cost (30000) gold
4. Go sleep with your wife.
5. Give food to your wife.
6. (Recommended from me) Never neglect your wife.

A few weeks or months will make your wife pregnant. Two kids maximum, by my standards so far.