My daughter is very sensitive to her surroundings, gets quite overwhelmed if a lot of noise/movement is going on around her. She can get quite teary. When in quieter social settings she is happiest being left alone to just observe very carefully what everyone does.
I see my family a couple of times a month, and certain members less. When doing the typical 'can I hold her?' and I pass her over, she is noticeably upset and anxious, like they are a threat. Anyways, it wasn't really worrying me, I just put it down to her being a sensitive child, and not really wanting to handled by people other than me and my DP. But my family say this is abnormal, and I should be trying to get her socialised, going out and spending more time with other babies etc.
Strangers have acted funny when she hasn't smiled at them when they have done their best effort... and I just think if I had some brainless person come in my face making silly noises, I would probably just stare at them weirdly too. My DD1 (now 6) had the same kind of upbringing, but was always indiscriminate about who she interacted with... so very different.