Introvert.
It didn't affect my instrument choice, we initially had a bout 6 guitarists, a drummer and a singer so all that was left for me was bass.
I was always the shy kid, the last to get picked for a team or volunteer for anything. Playing in a band initially scared me to death, I was a bag of nerves before going on and well into the first set.
As time went on (50+years) the nerves got less and now I don't give it a second thought. I'm up at the front of the stage singing (some lead) without a care but as soon as the gig ends I need to be on my own.
The other 2 in the band will stop for a coffee or a meal on the way home but once my head is set for home nothing stops me. I make the excuse that I don't feel comfortable leaving my gear unattended in the car, which is true but only part of the reason.