The villagers rarely produce equal numbers of boys and girls; the genders are randomly determined. In real life I have only grandsons and no granddaughters.
There has been a lot of discussion in the forum about that situation ever since Village Sim was released in early 2005.

The gender imbalance usually corrects itself. If you start to get in a real bind, you can always research Medicine tech to prolong the lives of the females that you DO have.