I don't know how old your kids are, but trust me -- if they are over 11, they likely have already seen more serious pornography on the Internet than you can imagine.
You really can't stop it. All you can do is help them handle it.
Most 13 year old girls have already seen more penises online than their moms have.
It’s one thing for a kid to run across it on their own, which is bad but I understand it happens. It’s a whole other thing if an adult is purposefully showing pictures to kids.
I’m not naive.