So the other day I was reading something on the web about what makes a person gay (it was related to the whole Virgina Tech thing in this guy's mind). Anyway, he related the old chestnut about absent / weak father and strong mother making someone gay.
And I thought, what if they are right about the circumstances, but wrong about the causality? Let's look at this from a purely biological function. There is some research that says gay genes (and I am talking male only here) run down the mother's genetic line, AND that the changes of a gay child increase as the number of children increase.
So let's say there is a gay child born in an hunter / gather type society. Well, the father has no interest in raising the child (from that whole "will further his genetic line" viewpoint). The child clearly will not pass his genes on. So he ignores the child and leaves him alone: hence absent father with this child
The mother, on the other hand, has an interest in the boy to stay around the fire as a strong or tall pair of hands to help. This would explain the whole "passed down the female genetic line" thing. So she helps to raise the child and teach him skills: hence strong mother.
These circumstance stay in place throughout most of history (the movement from hunter / gatherer to farming to feudal systems).
From a genetic standpoint, once you have a child, the genetic need for multiple children reduces - this would explain why subsequent children have a higher incidence of homosexuality.
In modern times, this would change as a gay child actual might further the family fortunes. In a modern / barter society, connections are important. From the family viewpoint a gay member of the family could increase contacts or wealth.
In recent times (with mass communication) gay people are expected to have unique skills (whether stereotype or true). Therefore, a gay child moves from hardship to neutral or positive - and the incidence of the "absent father" reduces.
If I am right, you would see this family change as a society progress from (the western thoughts) of "traditional" to "modern". It isn't just that being gay is accepted. It is that there are skills that are useful to the genetic family.
Of course, there is also the possability that I have chosen the explanation to fit the facts - given my predisposition to see the whole gay thing as "normal". But that is a mobias strip of causality I don't want to get into.
(I wish Ed would come home too. My brain hurts.)