"well, I suppose we were given one specific example from ancient history,"

Sorry pete, Don's conjecture is complete bullshit.
Ikhnaton, Akhenaton, Amenhotep 4th, was married to a daughter of his fathers brother,(Nefertiti) and within ten years she had produced to Ikhnaton six daughters. He, his wife and family are depicted on many ancient Egyptian reliefs. It is said that Ikhnaton was devoted to his wife and family ....it was unusual for Royal family groups to be produced at that time.

The deaths of Ikhnaton and Nefertiti are shrouded in mystery but it is known that one of his daughters became ruler after his death.
There was also another female ruler before the daughter who some scholars believe may have been Nefertiti herself, if she survived Ikhnaton
The daughter in turn married and ruled with Smenkhkare, a shadowy figure, of whom very little is known.

Ikhnaton, (Akhenaton), promoted the worship of nature and chiefly the sun, the ultimate life force, he forbade the worship of the numerous gods of the old kingdom and introduced the first monotheist religion.
Some Scholars believe that the 18th dynasty king was Moses...of the Old testament.