I think what gender you get is random, or pre-determined by some sort of other pattern, but you can't choose. Whether the matchmaker's book was open or closed didn't make a difference for me; on my v1, now, I usually get boy girl boy girl with some deviations but not many. You can't choose your gender, but eventually you will get both in your family line; I've never heard of a tama going 30-some generations of only males or only females!