How to tell if someone had a good childhood?

Just look at whether they are timid, thin-skinned, and insecure, always feeling not good enough.
Being timid comes from being frequently frightened in early years, being thin-skinned comes from being frequently shamed in early years, and being insecure comes from being frequently denied and belittled in early years.
Fear, shame, and insecurity are the three mountains weighing down on a person.