Think of the children...
<sarcasm>
Clearly, there is only one way to have sex:
1) It must be Missionary (No Adventures)
2) It must be pleasure-less.
3) It's only for making more of us.
<\sarcasm>
Porn isn't going around trying to get 6-14 year olds clicking all over. They usually are catering to a category or multiple categories, based on your particular fetish. I would suggest most parental filters are going to do their job and pickup most porn sites and block them.
Outside of that if your child is looking for porn, I am going to going to venture that have an interest in sex and sexuality. This about the time you need to be a parent and talk to them about sex. You don't need to admonish your child because naked bodies peaked an interest,