There is a concept I came across several years ago that I truly believe has had a large effect on my psyche, not just in terms of orientation, but also some of my other emotional issues. That concept is called "touch hunger" (also known as "skin hunger", but I will be speaking more on that below).
In brief, it refers to the idea that human beings require a certain amount of affectionate touch in order to thrive… and in the West, they aren't always getting it. Oh, when a baby is born, in most cultures, it spends much of its time in close proximity to its mother. And, for the first couple of years or so, a child only has to wobble over to a parent, arms outstretched, to be picked up and held. But after a while, that activity ceases. Kids are expected to socialize with their peers, primarily in a school setting. At least at the beginning, affectionate physical contact is acceptable, if occasionally unexpected.
[True story: On my very first day of kindergarten, a boy walked up and hugged me hello. This actually freaked me out a bit, because my own upbringing was a bit more standoffish than most, despite my Italian-American upbringing. (My parents weren't huggers, and while I did have an aunt or two who were, it wasn't so much affectionate as smothering. Seriously... bears could have taken lessons. ) ]
This does not last. As youngsters become pre-teens, the idea of touching your peers with anything more than a handshake or a slap on the back slowly but surely becomes socially awkward, especially with boys. They are expected to be tough, and self-reliant. Showing tenderness to a peer would be construed as a sign of weakness at best... and as they aged, a signifier of their possible orientation.
And touching a girl? By the time they even admit girls exist, practically any sort of contact, affectionate or otherwise, is construed romantically. Do you remember "$BOY and $GIRL sitting in a tree..."? I will confess that I do not know whether girls are allowed to hug other girls, or at what age it becomes coded as a romantic or sexual signal. But I would suspect that the transition happens later than with boys.
Meanwhile, any other role models they may have are pretty much exclusively hands-off. I don't believe I need to explain why.
They don't get touch from their parents. They don't get it from their peers. And they CAN'T get it from other adults. So they get older, and the hormones kick in, and suddenly, they are expected to pair up with a peer of the opposite gender (or, more progressive areas, any gender) and enter into a romantic relationship... which is expected to turn sexual after a certain age. At this point, affectionate touch is hardwired as a form of foreplay.
But what is an aro/ace to do? Stay at home, starving for a tender touch. After a while, at least for me, it transitions into a need for skin-to-skin contact beyond handshakes. I tend to call this skin hunger, as it's a degree beyond clothed hugs and the like. Of course, this is nearly impossible to experience in any relationship, same-gender or otherwise, without it being interpreted as a prelude to something else... and I must confess, the last "romantic" relationship I had, approximately 2 decades ago, was basically an excuse to achieve the touch I really needed.
It did not end well, which may be part of the reason why my preference these days has switched to those of my own gender. Impossible to say, at this juncture.
There are glimmers of hope, however. There are other cultures, primarily Japanese & South Korean, where the idea of older teens showing affection is more acceptable. And I've also seen younger actors & performers show affection to each other in public, something which would almost certainly have been controversial when I was their age. But as things stand now, we have generations of children, male, female, or other, who are not getting the affection they need... and that can turn them into broken folks like me….
Requested/suggested by @Coyote.