I see what you're saying but i don't agree. I was given a lot of attention when i was young, from a baby, as i was first born, and i remember being a toddler and hating it even then. I even started pulling my hair out (trichotillomania) from a baby due to the stress of being with people (except my mum, she was like my safe place.) So i definitely believe we can be born introverted. I think it's part genetics, part learned behavior. My mother is an introvert, my father more extrovert...so i guess i could have gone either way. Unfortunately i went the wrong way.