As a member of the LGBTQ community, I fully agree.
I’ve believed that we are a mix of nature and nurture for as long as I can remember, and it stands to reason that sexuality is a part of that. I also think the vast majority of people are far more sexually fluid than they would admit due to cultural stigma. Not everyone is bi, but I do think there’s a bell curve.
That said. I do also believe that people are born the way they are and the nurture aspect is more of a determining factor for how they express not who they are. I was raised and socialized as a straight male but realized in my 30’s that I’m queer and non-binary. Realizing that put so much context to the struggles I had growing up on a Christian environment and solidified for me that this is who I am, despite how I was nurtured. But had I not gotten out of the religion, I’d have never changed and just silently suffered and struggled until I died. My expression wouldn’t have changed who I am, only how I acted.