Eldest or only children often prefer the company of adults over other children, 2nd and further or kids from bigger families tend to be more comfortable hanging

Eldest or only children often prefer the company of adults over other children, 2nd and further or kids from bigger families tend to be more comfortable hanging out with other kids. I think it's largely practice / what they are accomodated to and it's pretty normal. It's also "point of reference" - kids more isolated from other kids will latch onto adults as their "reference people" they compare themselves to and model behaviours from while kids more socialised with kids will reference more onto near peers. Isolated kids are commonly more intellectually precocious but less directly practical and (naturally) tend to have a bit more trouble connecting with peers. It's not unusual.