In my experience, the word 'scooch' is not a frequently used word in the US. Therefore, I would tend to stay away from using it.
If I wanted someone to move their buttocks (body) I would say "Please scoot over a little bit! I need more room."
I see no reason to use the word 'scooch' with your parents, or with anyone else for that matter!
If you think a word might be 'taboo', don't use it without expecting consequences!