Two chldren per couple, and I usually control that so each family has a girl and a boy. The first child is a surprise and if it's a boy/girl then the second one will always be a girl/boy because I use the food and music cheats. I am such a control freak when it comes to my worlds and the population balance. I play rotationally with aging off and age up my Sims based on the story I created for each save. But that doesn't mean the game doesn't throw some suprises at me from time to time in spite of my controlling ways. It doesn't happen very often but it's always funny, and I deal with it. LOL
