it doesnt lessen the, value but depending on your education level (i know that america starts school a year after scotland, and some schools in scotland have brought their Standard Grade exams forward a year) you might not know enough about the subject for it to be correct more than, say, a 20 year olds.
however, there are 10 year olds who are smarter than people older than them, and they study the subject at a higher level.
of course, the subject might be sex and your school might not do even basic sex ed then (my school did very basic sex ed when we were 9/10, but more in depth at 15) you wont know much or have practical experience.
so if you're normal 10 year old, its more likely to be wrong, but not less important. if you're smarter than the average, its less likely to be wrong. if youre 70, its likely to be wrong because of now-outdated education, but you have experience. nobody's opinion matters more, only whether or not its right.