Those who seek attention, seek it because they have so little meaning in life, that they are willing to further destroy themselves so they can be seen, and since people give LGBTQ+ people get so much attention, narcissists and attention seekers often believe becoming LGBTQ+ will somehow grow their ego.
Your right, sexual orientation does not really affect the body physically, that's why it's less of a problem then Transgenderism, which mutilates the body and can cause serious health problems, though, it can affect people mentally, oftentimes, those relationships gay people have don't really last long, and gay people are more likely to have suicidal thoughts.
13 and 14 are pretty much the minimal age that I'm willing to accept, because that's when people start having relationships and having their first kisses and stuff like that.
We really don't know if being Gay is a choice or not, it's sort of a mystery, it's possible it's an underlying mental thing, and only shows itself at a certain age.
I do however, have a theory as to why Gayness is becoming increasingly common, and I believe it has something to do with Soy, it's often put in babies milk bottles, often as an alternative to breastfeeding, and when fed to babies, it could likely affect their genes, and mentally set them to eventually become Gay, and since Soy contains Estrogen, AKA the female hormone, and females are usually attracted to Men, it's possible it's causing the sexual orientation of those Male babies to eventually mimic Female heterosexuality, which is why these Men end up becoming attracted to Men.
But, like I said, it's just a theory.