Moral Identity, do you know the reason why?

Mother insisted that we should never leave our hats on the bed. She insisted because her mother had told her this as a child. You just never leave your hat on the bed.
When grand-mother was asked about this "must carry out" rule, she simply replied that back when mother was a child there was an outbreak of head-lice at school, so she banned all the children from putting their hats on the bed during that period.