Adelphogamy

But, however true it may be that all of the products of adelphogamy have but a single mother, we cannot ignore the fact that they have divers fathers.

But she also asked about the civic organization of our state : whether our queens were adopted or whether we insured the continuity of our dynasty by adelphogamy.

[…] at other times, and indeed rather frequently, the union of brother and sister, or adelphogamy, as the entomologists call it, is accomplished in the nest itself; for our humble heroines find it easier than we do to modify, in case of need, their fundamental laws, or even to reverse them, adapting themselves to circumstances, and turning these to account.

Concerning the system of polyandry among the Todas, I gather that a woman may be married to more than one man, provided they are brothers (adelphogamy), and the maximum number of husbands seems to be five.

While there are obscure (and presumptively vestigial) traces of polyandry or adelphogamy, and while an informal polygyny is practiced by the chiefs and older warriors, the formal matings are between one man and one woman, and appear to be permanent.

The tradition is quite different from the Han-Chinese, but may have the same origin as the adelphogamy of the Tibetan people, or be a variation of it.

What made Tiye encourage her children to engage in adelphogamy, especially given that Semenkhkara had already become a victim?