Should sex education start in middle school or high school

When I was in sixth grade, I remember having to get a permission slip signed from my mom to be in a health class where the teacher taught about sex. Then later on in tenth grade I took health again because it was required.

So where should sex education start for kids? At home with the parents(any age ) , middle school, or high school.

Additional questions:

What topics do you think should be most important to discuss during these classes?

Would you give your child permission to learn about sexual health in class?

Would you go in more depth about sexual health with your child from what they learned each day if they had questions?