A new field in genetics is "Epigenetics," and it goes beyond just genes and chromosomes.
There are scientific journal articles, and videos on YouTube. An entity called "CARTA," under the auspices of UC San Diego, deals with the subject for instance.
They are NOT studying homosexuality. They ARE studying human genetics, migrations, various aspects of populations down through the ages.
It is a big topic. Most people will not even start to study it. It is easier to have uninformed opinions that way.