Incest was very prevalent amidst the Egyptians (and most other ancient peoples, except for the Jews). Brothers and sisters routinely married...with awful consequences.
The dynasties which took that more seriously tended to crash and burn (the 18th for example); OTOH, the Ptolemaic (post-Alexander) dynasty inbred the sons and daughters for generation, and wound up with Cleopatra VII (the famous one). But OSAH the 19th (Ramses II “the Great” et al) was insurgent (they came from nowhere and just took over) and he had lots of different wives and hundreds of children, just to hedge his bets. Chances are that Ramses II has many millions of living descendants.
Quite true, now a days the remnants of these unions are relegated to the DNC and pro-liberal groups.
Just sayin!