For the record, my post on BMG that LGBT posters forced the editors to delete was about how there is indeed an unchanging constant element to marriage throughout history. I said that I'd read both Stephanie Koontz's and David Blankenhorn's recent histories of marriage specifically looking for any mention of marriages that did not have a right to conceive children together, and found none, zero. Every marriage, everywhere, had a right to have sex and conceive children together, using their own genes. There was a lead-in about how both sides of the debate bring up the same debunked points over and over again, and I mentioned how people sometimes try to prove me wrong by bringing up those infertile-cousin marriages and incarcerated prisoner marriages, but in neither case is the couple prohibited from conceiving children. That was pretty much the whole comment, it didn't even mention the issue of same-sex conception.