Well, unless you want a population explosion on your hands, a female breeder is easier to control. At least if she gets enough breeding skill to wander off and breed on her own, she's got 2 years to mind the baby. A male breeder on the other hand, (and I'm trying not to be nasty and compare this with real life.. lol), will go around merrily impregnating every female in sight - and the more skill he gets, the worse it gets.