Sexual attraction in humans is induced by a hormonal secretion controlled by the hypothalamus called gonadotropin.

It secretes what's called luteinizing and follicle-stimulating hormones that mature the stimulation of the gonads (i.e., testes in males, ovaries in females). You can get a brief introduction of how it works here: https://www.britannica.com/science/gonadotropin

The basic gist is that the anterior pituitary gland's secretion from these hormonal gonadotroph cells work as neurotransmitters in humans for what we call sexual attraction, as they help humans to perceive what they find sexually stimulating.

It requires a steady maturation of the gonads leading up to puberty before they develop enough for reproduction purposes. Without gonadotropin, or the maturation of the gonads leading up to puberty, it means the individual is left infertile. You can get the short gist of it here: https://www.news-medical.net/health/Gonadotrophin-Hormones.aspx

This is oftentimes why intersex individuals or hermaphrodites can neither inseminate nor gestate eggs.

(I know this is taking a while, but bear with me, I'll get to the juicy bits)

The hypothalamus' secretion of these hormones happens over a maturation period as well, thus it requires environmental stimuli and physiological growth in order to induce the steps necessary for gonadotropin to start the neurotransmission process.

And here is where things get fascinating, the hypothalamus hormonal secretion during prenatal phases only initially helps to define the sexes (i.e., ovaries and testes), but becomes nearly latent for sexual development until puberty. It's explained here: https://embryology.med.unsw.edu.au/embryology/index.php/Endocrine_-_Hypothalamus_Development

The progenitor cells necessary for the development of the hypothalamus requires consistent and constant environmental stimuli, leading up to its maturation and the process of putting gonadotropin to use for developing the gonads.

In short, immediate postnatal hypothalamus functionality is at less than 20%. Because during the neonatal and prenatal phases, the hypothalamus is only secreting the necessary hormones in a light pulsating manner to develop gender differentiation between males and females: https://pubmed.ncbi.nlm.nih.gov/7643957/

Dimorphic differentiation between the sexes for the hypothalamus growth occurs rapidly during the formative years, usually as toddlers.

It's not until the pubescent years where the hypothalamus begins to rapidly and aggressive release gonadotropins based on sensory stimulation (e.g., touch, sound, smell, sight, and taste). It's further explained here: https://www.sciencedirect.com/topics/immunology-and-microbiology/gonadotropin-release

This only occurs due to stimulated growth from environmental stimuli, as the human body needs sensory input to react and evolve based on said stimuli.

TL;DR What we perceive as sexual attraction is based on neurotransmitters that require complex development over the course of years. The actual neurotransmission process only occurs as a postnatal development (i.e., after someone is born).

TL;DR Part II The only time that human beings will encounter sexual maturation during formative/prepubescent years is due to early environmental stimulation that causes gonadotropin to secrete before puberty. This usually only occurs with aggressive promiscuity, abuse, or molestation, which is found to be quite common in gay men and lesbian women: https://pubmed.ncbi.nlm.nih.gov/11501300/

TL;DR Part III It's more difficult to reorient a male's sexual attraction after puberty, which is why Leftist work so hard to influence male sexual behavior during formative years. Trauma, abuse, and molestation contribute greatly to reorienting someone's sexual behavior/attraction, and said stimuli is necessary to change someone's orientation before it becomes stabilized during pubescent years: https://link.springer.com/article/10.1007/s10508-012-0021-9

Said trauma/abuse can have long lasting effects on someone's psychological and physiological development, including their orientation: https://www.youtube.com/watch?v=4ClnMR3IgYI

TL;DR Part IV Even Left-wing media had to concede there is no gay gene: https://pubmed.ncbi.nlm.nih.gov/31481774/

This is because sexual attraction is based on environmental stimuli, and it can change over time based on epigenetic influence: https://www.nature.com/articles/s41574-020-0370-8

Most studies thereafter continue to promote the myth that there's biogenetic factors, but all studies only include homosexual adults who have already been altered by epigenetic influence, as opposed studies including neonatal development juxtaposed with adults in a longitudinal study: https://pubmed.ncbi.nlm.nih.gov/31467194/

Basically, PMC7082777 is the equivalent of rounding up a bunch of MMA fighters and doing a study on their reaction times and durability compared to non-MMA fighters and concluding there is a genetic difference between the reaction times and durability between MMA fighters and non-MMA fighters. Of course, there would be differences since the epigenetic influence has already been impacted and the gene expression is taking place AFTER the change has occurred.

It's also the equivalent of finding heroin addicts and concluding that there are genetic differences between them and non-heroin addicts, even though the measurement is taking place AFTER the stimulation has already impacted their physiology: https://www.dana.org/article/heroin-addiction-linked-to-long-term-brain-changes/

TL;DR for the TL;DR: You can't be born gay because the neurotransmitters required to perceive sexuality don't develop/secrete until puberty. The only time they secrete early is due to molestation/rape/trauma. This is why there is no gay gene, and why it's physiologically impossible to be born gay since the organ development to express sexual behavior hasn't matured enough during neonatal years to allow said expression, which requires sensory stimuli, which only occurs as a postnatal development.