Why are some kids friendly vs others unfriendly ? Is it a case of upbringing ?

[lemonsa]

I have two sisters.

They both have kids. One sister's kids are super friendly and affectionate and the my other sister's kids just aren't.

The ' unfriendly ' kids are a bit friendlier now they're older, but when they were younger ( under 5 ), they wanted nothing to do with anyone other then their mum pretty much. No matter what you do to engage them in play etc, their friendliness doesn't last long and they ultimately run off/ don't want to engage much.

The ' friendly ' kids are really friendly towards extended family and enjoy playing with us for longer periods and it's just easier to form relationships.

There are no other differences as we see the kids on both sides the same amount and make the same efforts.

What does this depend on ? Just the kids or is this also how they're being raised ?

People’s personalities vary…

"Unfriendly" often means shy. My youngest is a very sweet kind girl but very shy from a young age. She

Probably just shy

I don't think its friendliness, what you're talking about seems to be some kids being more outgoing than others.

I have one shy and one really outgoing. So I would say one takes after DH and one after me. Nothing to do with friendliness.

Combination of genetics and upbringing I would say! Just like adults.

Both.
My sons were friendly kids. My daughter wasn't and still isn't at 13 (introverted, rather than unfriendly).
My sister's kids are very friendly but also incredibly hyper/hard work. Partly ADHD and partly parenting.
My brothers kids barely spoke a word to anyone and were practically mute when they started school. They now live with him as their mum has MH issues and was considered to have caused a lot of their problems (she basically had them glued to her all the time and never let them go to anyone else and was very controlling). They've really come out of the shells now they've had a year with their Dad.

Theres extremes at either end that are unhealthy/a problem and there's normal variation between children and families and some is nature and some is nurture.

Perhaps it is related to how used they are to socialising but a lot of it will be temperament. They could be really friendly, sweet kids but you don't really see it unless you see them all the time. Lots of adults like this too.

@lemonsa
It is not uncommon to see families where 1 child may be very outgoing and friendly and yet another sibling is shy and withdrawn. So many different factors inform personalities and behavioral responses.

My eldest was shy and less outgoing towards extended family as a small child. The other was more outgoing and more familiar with extended family from a young age. Just different personalities.

Some people, including children, are just more reserved, shy or introverted. It's just how they are, it's not a failing.

Kids are people. People are different. Friendliness is often about confidence and being extrovert, not about whether someone is really a good friend or not. Take people - especially kids - on their own merits and try to not compare them so much.