6 year old masturbating?

is it normal for my 6 year old sister to masturbate a lot? she does literally ALL the time. anywhere. in her room, living room, kitchen, grocery store, and at restaurants while i’m sitting beside her trying to eat. she’ll just walk around the house with her hand in her pants 24/7. it makes me uncomfortable and no matter how much we tell her to stop she doesn’t. i didn’t know what group this would go in but this one seem appropriate