A normal functioning adult is what they would become.
Most teens find a way to read and look at nudity and erotica. And if they can't, they often go out and find someone to have sex with. This is something they do without first learning about safety, such as using protection and understanding that they deserve the right to say "no" and "stop" whenever their partner does something they are uncomfortable with. What this can lead to is STDs spreading, teenage pregnancies, and even rape since uneducated teens do not understand consent.
Your teens will find a way to discover sexuality no matter what you do. You choose for yourself if you want to let them do it the safe way (erotica, education, and eventually protection when they are old enough) or the unsafe way (running off to an unsafe place with a classmate to have unsafe sex that they hide from their parents. Huge risk of pregnancy and STDs).
For the teens I care about, I would prefer them to discover it the safe way.
Letting your teen explore their sexuality from the safety of their home, and making sure to tell them that they do not have to have sex before they are ready (teens tend to stress each other out and brag about losing their virginity, and it often ends up in people doing it before they are ready), is probably the best thing you can do to protect your teen from harm.
Also, in the age of the internet, erotica is NOT what you should be afraid of. What you should be afraid of is online predators.
The best thing you can do is to tell them that they are valuable, smart and deserve the best. And that when someone is trying to talk them into sending nudes etc that they should say no and stop talking to that person.