DD2 was the same. Just her way. When my elder DBs spoke to her she'd turn her face away immediately. She was like that with most men, even though those she met were family members.
I didn't fuss about it, and she grew out of it. If she's ever reminded she just laughs. She gets on extremely well with her uncles.
I wonder if it was because men tend to be talker, deeper voices etc in a family gathering they're heard the most. But I don't know.
DD2 is quieter than her sister. Not over-quiet, but happy not to be around people so much, doesn't like to feel bombarded. I've realised that over the years. Shes still like that aged 22. & it's fine, we all have our personalities. Maybe your little one is the same?
What I will say is my DBs were kind and loving to DD2, no fuss or questions re her little meltdowns. No insisting on holding her if she didn't want to be held. They were calm about it. What pp's are saying on thread makes good sense.
When I was little I'd scream and cry when I saw my godfather. When I grew up I realised it was due to him being a big tall man, big face, big hair. Maybe I saw 'monster'😁. But he's lovely, like my 2nd dad now. The minds of children...who knows