But it got me thinking, if there's a gay gene, and evolution works by passing off the best genes through reproduction, and gays can't reproduce.... Well, then how does that make sense?

There were never any gay genes. Even Lefty scientists had to finally admit the ruse was up: https://pubmed.ncbi.nlm.nih.gov/31481774/

It was a falsehood spread by literal gay propagandists back in the 1980s with ZERO science supporting it. All actual hard sciences show zero biological traits of gay genetics, gay endocrinology, or gay neurophysiology.

It's all behavioural.

There's a great psychogenic profile explaining the phenomenon here, and how there is no gay gene and never was, and that a lot of propaganda was used to confuse people about the origins homosexuality (i.e., most times it's spawned from grooming): https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6026959/

If you want the actual scientific breakdown of why homosexuality cannot be genetic due to a number of factors, you can check out the older comment permalinks here, but they're quite lengthy:

https://archive.ph/p4csm

https://kotakuinaction2.win/p/141YWlHPh3/x/c/4OTPNQp5PaK

https://kotakuinaction2.win/p/141F1CVn6N/x/c/4JKzDPN4Hvn