We call it mannerism Doc and Arth.
Most children who used to have breast feeding from their Mom developed mannerism. I don't know but sometimes baby couldn't sleep without breasfeeding on the right breast whilst other hand of baby is at her mother's left breast. It is their habits sometimes and developed mannerismuntil they fell to sleep.
They started to develop bad mannerism during their childhood.
I have also friend who got her mannerism sucking her thumb until we reached high school. During our elementary early days, she was still carrying her feeding bottle. She stopped but, but developed sucking her thumb.![]()