Follow up question: does this have any link with consanguineous marriage among royalty and nobility in the Zoroastrian greater Persia that came before it, and the brother-sister marriages of the Egyptian Ptolemaic dynasty?

This interested me, and I tried to seek out some data regarding this type of marriage in Australia, as one of our states, Tasmania, is often stereotyped as incestuous and backwards. Can anyone suggest where I may find out about this?

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