- May 2012
I was wondering about the effects of sibling marriage, such as in ancient Egypt among the pharaohs and if it caused genetic problems.
At some point, they almost certainly made the connection between incest and birth defects. The tendency toward keeping it in the family among royals notwithstanding, I think we get an indication of that from ancient codes of behavior specifying prohibitions against sexual relations between close family members. Examples would include the Hebrew Bible and the Code of the Nesilim.Greek mythology has a huge number of incest relationships - fathers and daughters; brothers and sisters; uncles and nieces; cousins - appearing across many generations (and not just among the gods who might be viewed as immune to human diseases). Similar relationships appear in other mythologies, but I don't believe in such profusion.
As far as I recall, mythologies never indicate physical abnormality in the offspring of these unions - in fact they are often shown as heroes and great leaders. Why would this be if the children of siblings/cousins have a higher chance of genetic problems? Did no one notice this in ancient cultures?
I don't believe this has anything to do with inbreeding. The original carrier of the hemophilia is believed to be Queen Victoria and many of her daughters and granddaughters, also carriers, married into royal and noble families throughout Europe so the defect was passed on this way. Hemophilia only needs one carrier to manifest in men - the issue with inbreeding is that the gene pool from both parents gets smaller and smaller. Alexei Romanov had hemophilia because his mother was a carrier and passed it onto him, not because his parents were second cousins, which is generally considered not closely related enough to significantly increase the risk of birth defeats.I know some royals like the child of the last tsar of the Romanovs had hemophilia and I think that's a genetic disorder which seems to have effected the nobility in some instances.