Sorry it's long and maybe more of a rant ...
My 2yo has developed some degree of strangers anxiety since he was 16-18 mo. It's a bit better now, he won't scream when he see people or anything, just doesn't like them coming too close and will take a while to approach them to play or anything that involves physical contact.
I'm getting a bit fed up with the comments or judgemental looks from visitors, mainly family members who constantly try to force interactions with him. Things like sitting right next to him when he is on the sofa, or trying to show him a toy - he will repeatedly say "no, no, no" but they still insist on approaching.
My parent is visiting and this morning I told them I was going to get dressed quickly, if they could have a look on the kids in the living room watching TV. 5 minutes later I hear my toddler screaming and when I came downstairs they had picked him up for a cuddle!
Part of it is cultural I think, my side of the family is European and a lot worse with this. I'm getting comments like "X kid was like this too as a child, but they're normal now", or "he's very clingy/territorial..." - when he is really not as he's barely showed any sign of jealousy when his sister was born, and he has been completely fine with sitters once we are not in sight.
With my British ILs I just feel judged, they don't push as much but you can see from their expression that they think we are keeping him away and that he is "difficult".
I might be a bit unreasonable, because at the end of the day we got 0 help from anyone in our families when he was born, and I'm still a bit resentful about this (although I understand it was their choice and I can't expect them to help).
I wish they had a closer bound but they barely come down to see us (particularly PILs who are retired and live an hour drive away), and any contact is initiated by us.
They wouldn't be "strangers" to him if had come to see him more often, I'm not sure what they expect us to do now really!