Programming Population Growth...

I felt like writing a small application tonight to project populations over time. Problem is, the more I think about population dynamics, the more confounding this project becomes.

I'm thinking, well if we have an average of 3 kids per two parents every 50 years, those kids will then do as their parents did and have an average of 3 kids per 50 years. But then at 70 years the parents are dead.

This application wouldn't consider terminal illnesses or diseases. That would make things a bit more complicated I'm sure.

Just curious how you guys would do this.