Why is it that humans have this innate urge to belong to something or 'fit-in'? why is it that we cannot be content or comfortable to just 'be'.

We are so afraid of feeling left out that some of us create facades that don't even truly represent ourselves in order to be accepted by others.

Is this just a natural human phenomenon that is imprinted within our genetic structure or is it a product of our interaction with society and a result of our upbringing?

What do we REALLY achieve by 'fitting-in' anyway?