I'm only now finally got to a generation (5th on my first game running) where they have so far had more girls than boys. Their first child was a boy and I feared the it would be mostly boys again. But now they have had 3 girls in a row. In my other 2 games, the kids have all moved out, but one family had 3 boys and the other had a boy, one girl, then twin boys. I'll have to remember to take a screenshot to show everybody my boy-dominated family trees haha.