Pf I asked my 13 year old cousins this year and like 5 years ago if they know her and they literally have no idea who that is. Anyone below the age of 18 just doesn't know her. They may recall some of her songs if they heard them though.
Her as in Britney? Eighteen years old seems unrealistic. I think it's just ppl below ten that don't really know her. But fair enough, at ten years old I didn't really know Madge, Kyle etc cuz I didn't care.