Should we be shocked? My gosh, we have men marrying men, male homos adopting young boys, Sandusky raping young boys, bo trying to legalize bestiality in the military, the mentally deranged transgenders that don’t even know what sex they are......... and the list goes on. Civilization has advanced no more than a day from 1000 BC.
My guess neolithic tribes were totally intolerant of incest and homo sexual behavior. As a matter of survival if nothing else.