It's nice to see confirmation of this. I got similar results on the simulation I wrote: http://github.com/philwelch/SexSim See my comment here: http://news.ycombinator.com/item?id=1407984

I'll check back when I'm less busy to compare how our simulations are set up. Mine was very quick and dirty and naive, based on uniform random distributions no less, so I'm fully open to the possibility we're both wrong.