I will check if its my kids who does not like to mingle with people, just being selective or is it an attitude issue

Yes definitely and we should ask them on what is the issue to help them make friends and be more social

There could be other underlying medical problems...need to consult a physician...eg. mild autism

I don’t think so. As Long as they’re happy. (Not ok if it makes them unhappy or depressed)

Yes, everyone need friends. I will check with my kid as to why is that happening

I would also want to take time to understand why is he/she unable to.

Can spend time with them to understand what support they need

I am so worried because my boy is weird around peers :(

yes!! especially @ the age where they can go to school

Social skills are important. So I would be concerned.