Because they were raised to be honest and their grades would never result in them being shamed, only helped more? Because discipline? Because they had nothing to fear from their parents?

Just some possible reasons to consider. I never had a problem showing my folks. I did fairly well but had my weak areas too. Even failed a class once and had to re-take the next year. But I was never afraid to tell my parents, I just felt disappointed with myself but I knew I had tried as best I could. That’s all they ever expected of me.

I’m really sorry if your experience was less ideal. Sincerely, I mean it.