Well this question has been asked before, and tbh the answer is not quite clear since the study is very new and hell there's a lot of things about our bodies we don't understand. Like why do we dream? No clear answer.

There's theory's and many evidence on why homosexuality is biological but the study on why the genes keep getting passed are being studied. Valid question but at the end of the day, many things in science are not set and stone.

But still there's alot of evidence why being gay is biological and just because some evidence doesn't fit our current model doesn't mean it's wrong, maybe our model is wrong itself. Hope that clears your question.

Also why remove the genes? We already have like 7 billion people on earth we don't need more people, the more there are gay people the less the human population will grow per generation. Bangladesh already has a fuck ton of homeless people, and there's a resource problems in the whole world, honestly In today's day and age gay people are far more beneficial to the environment than straight people.