How is the "Gay Gene" alive?

 

The record of Egyptians was not as long as the Chinese history. 

Chinese history had recorded few thousands ago, the emperor was a gay. Of course, the common people were lots of them homosexual without recording but lived a happy life. 

For thousands of years, homosexual is endlessly seen from here and there especially in the internet age, it is much available. 

Of course, homosexual is borne but not a choice. 

Now we know that there is no heterosexual on earth, thus, those got married and have children were not 100% a heterosexual unless they have done the Kinsey Scale Test  https://www.idrlabs.com/kinsey-scale/test.php

How is the "Gay Gene" alive? Evolutionary Biologist Richard Dawkins Explains