And this probably goes without saying, but plenty of LGBTQ people have children. Being bisexual, gay or transgender does not preclude reproducing.

But even if it did, bisexual, gay, and transgender people are often as not the children of cis straight people. Almost literally nobody thinks people with minority gender identity or sexual orientation exist because of classic mendelian genetics.

The idea of a "gay gene" is hopelessly naive. Though, clearly there is some sort of complex genetic component to being gay, and very probably to being trans. But that component, however it might arise, does not exist because gay people pass on their sexual identity on to their offspring.

Human sexuality is tremendously complex, and identity develops in individual humans through a complex process involving genetic potential, gestational development, and other pre and perinatal environmental factors.

Nobody can pin down the factors that combined to see to it that I experience no sexual attraction to women and lots of sexual attraction to men. But people like me have existed since as far back as we're able to peer in human history.

That indicates we're just a normal, minority variant of human. Whether or not we reproduce will almost certainly have no impact on whether people like us are born in future. Because being gay isn't about passing on traits. It's about being human.