It could be linked to those, but it doesn't have to be linked to anything, any more than any other sexual identity is. But if your identity is influenced by ASD or an illness or life experience, it's still valid. And if your identity changes in the future, that's okay, too. There's no wrong way to identify.
My psychiatrist grilled me hard about it. It was gross. There is definitely a phobia and erasure of aro spectrum and ace spectrum people. Hopefully in time it will gain more recognition and people won't act like there's something wrong with us.
I'm 31, never been attracted, knew since childhood I wasn't interested. It took a long time to learn about asexuality and longer to realize that's what I am!