Why did Genghis Khan have so many descendants?

Some time ago, there was news that Taylor Smith was a famous expert in human genetics. In 2003, he made a controversial research on Genghis Khan's genetic test. According to his research, about160,000 people are descendants of Genghis Khan.

In fact, through simple calculation, we will find that this is a very boring conclusion.

Genghis Khan lived in 12 century, and now it is 2 1 century, separated by 900 years, with 20 years as a generation and 45 generations. With the high birth rate in ancient times, it is conservatively estimated that each of his descendants has an average of two offspring. Suppose he has two children, and each of his children has two children, so he has four grandchildren, four grandchildren and eight great-grandchildren, and so on ..... So Genghis Khan should have 2 45 descendants, about 35 trillion. This number far exceeds the total population. What's wrong with it? The reason for this phenomenon is that with the passage of time, there are more and more descendants, and the number of intermarriages between descendants increases.

Similarly, everyone in the 12 century has so many descendants.

Conversely, we can infer how many ancestors modern people have. Everyone has parents (two in the first generation), and parents have their own parents (four in the second generation), eight in the third generation and 35 trillion in the forty-fifth generation. This far exceeded the total population at that time, because the mother tree of human beings was not a tree in the strict sense, and there was also fusion between branches, that is, people with the same blood in their ancestors were combined.

Therefore, human genes are constantly merging, and it can be said that every two contemporary people are related by blood.