And in more places than ever before, including music videos, websites and social media.
So it's not surprising that sometimes children's sexual development can seem out of step with their age.
It's important that you have a good idea of what's normal sexual behaviour and can also spot the warning signs if something might not be quite right.
There are 4 phases of childhood sexual development.
As children get older it’s important to talk about sexually transmitted infections (STIs), contraception and pregnancy.