In the Animal Kingdom - where 'Alpha' males get to breed with all the females during their 'reign' as Prime Seeder, until replaced with the next male to take over...
...this brings a very restricted and compromised 'variety' of the male DNA in the animal gene pool of that species.
The 'Females' are varied because they 'all' get to breed. But only One male for just one or two generations gets to breed.
This is what makes the difference between Humans and Animals. There is more 'variety' and complexity in the Human Gene Pool because 'all' males get to breed with 'all females'.
It's this 'variation' in genetics that spawns more complex evolution (superior).
You could say (and has been said so, by experts) that the Neanderthals, Denisovians and Nadali in Africa were all basically 'outbred' by the emerging Sapiens because they were more varied in their genetic make-up and more 'MONGREL' in their genetic diversity (to adapt).
So when you hear of these things like Kings, Pharaohs, Emperors, Khans, etc - all planting their singular seed in many many females to establish a 'pure' male line. What they are doing is breeding Sapiens that are strong in diversity with their female genetics, but very weak and 'simple' in their male genetics.
In other words - domination by a single individual outbreeding other males in the Tribe so to speak, actually creates 'weaker' males and probably less intelligent too... much like an Animal.
Genetic variety, diversity, complexity is what made the difference between Homo species and Animals in the evolution.
In other words - the more diversity genetically, the faster acceleration of 'evolution'.
...so chances are that the descendents of Ghengis Kan da Roota! Are all a lot 'simpler' and 'weaker' on the male side of genetics, considering they all probably bred again with one another - passing on that 'pure', but compromised lack of Male diversity and genetic weaknesses.
Let's not talk about the Hapsburgs either.

Ghengis Khan: "I have sired 100 children! But their children all look a bit wonky for some reason?

"
In Libya, being a pretty 'closed' country due to Gaddaffi's legacy - now has the highest amount of genetic 'flaws' like Deaf, Dumb & Blind. This is due to the fact that although a Libyan from one side of the country, mates with another Libyan from the other side of the country - chances are high that they are 'very' related still. Thus the lack of genetic diversity is compromising their gene pool in the country.
They are becoming physically and mentally weaker and 'education and knowledge' can only go so far like a wheelchair for them.
Makes me wonder though about the Gene Pools of the Aborigines, let alone the Islanders of the Pacific, even if they are 800 years of isolation compared to 40,000 years plus.