Prima nocta goes back to the Epic of Gilgamesh wherein 'nobles' had the unholy right to take other people's virginity, whether they be male or female. The practice has been referenced right through to the end of the medieval era.
Gilgamesh lived in Uruk close to present day Babylon. Unfortunately nothing much has changed in the region and those whose bloodlines can be traced back to the 'noble' class of Uruk/Babylon have continued similar abuses on their fellow man/woman to this day with age of the victim a moot point.
Prima nocta had little to do with the infusion of noble blood into the general population and more to do with depraved psychopathic tendencies amongst the blue-bloods.
