Shyness In Children

I'm doing a paper on which a child becomes shy in childhood. I need the state psychological theories as evidence. Help!

My father was basically never in my life and my mother had a time out as a single mother -
I'm running
I was a kid ugly
There are many other reasons
good luck:)

there must be specific circumstanses such as parents who verbally demoralize their children were prevented from speaking by scolding them when they do not esteem plays a big so.Self part.There must be a cause and effect that can reasonably expect.