Maybe this is crazy but I kept track of the breeding in a notebook. After a couple generations I made a list of proper child-bearing age women, and investigated which men were not closely related (by looking back at my notebook). Then I would hook them up appropriately. Most of the time I didn't let them randomly mate - but sometimes I would hear a "kiss" and then look at who was coming out of the love-shack, and be shocked to find a 74 year old mother who had just hooked up with her 26 year old son (and had a baby!) or some other such random hook-up. I kept track until the population hit 55, but then I was so worried about so much food piling up that I got 10 women pregnant at once to take them out of the fishing/farming line. However, I don't know whose baby is whose. Oh well, best intentions.