I won't speak on if his parents did what was right when he was a teen, because none of us know the FULL story. But I will speak on what I can do now with my own teens and pre-teen. Some lessons I learned the hard way, and some are gleaned from others wiser than I.
Talk to your kids about sex.
If you don't, someone else will. And it most likely will not be someone with their best interests in mind. You absolutely have to teach them that it is okay to come to you honestly. And moms, DO NOT FREAK OUT. They will not be open and honest if you are going to yell, cry, or lose it. Pray for strength and breathe deep because I'm going to be honest with you: It's not IF your kids see pornography, it's WHEN they see it. It's going to happen and you need to be prepared for it. Open that door with your children and let them know that you are someone they can talk to. If your kids are younger, keep it age appropriate. But if they are older, don't be afraid to be blunt with them.
Know that pornography is addicting.
This isn't just a battle of the will, but something that will lead to serious addiction. Our family has a history of alcoholism and I've seen first hand the destruction it can cause. From early on I have talked to my boys about it and warned them that the seeds of alcoholism are in them too. And after lots of talks with others, I can tell you that pornography sears into the brain in a way similar to alcoholism and drug addiction and can "re-wire" the mind. It's nothing to mess with, even a little bit. Be honest with your kids about the damage it causes. Even honest non-believers will admit it is an all encompassing habit that is destructive and hard to break.
Teach them to guard their hearts.
From early on, we tried to teach our boys to "bounce their eyes" during pretty much every commercial during football season or any other place or time they saw an immodestly dressed girl. Teach your children to look away. Teach them that it's not "How far can I go before this is sin?" but rather "How can I keep myself pure?"
Pornography affects both girls and boys. Know who your kids' friends are, where they are going, and what they are doing, playing, reading. Be in their business. Pay attention to video games, tv shows, tablet games, internet use. We can be super proactive and shut down everything in the house, password protect the wifi, block the internet access, and set blocks on electronics, but don't let that lull you into a false sense of security. There are always new ways to do what your heart desires. We need to give them the tools to FIGHT this. Lock down what you can, pay attention to what they're doing, but then teach them how to respond responsibly. Teach them that their heart is deceitful above all else and to be constantly renewing their mind.
Teach them to FLEE from sin.
None of us is "strong enough" to handle sin. None of us. We are all sinful creatures and there is a constant battle going on for our hearts. Satan cannot take away a believer's salvation, but he can totally smear and destroy their lives. And he's really, really good at it. Teach them that this is a very slippery slope. One step on it leads to another and before they realize it, they can be in a place they never thought they'd be. Teach them not to even go look over the edge of that slope, because the ground is very unstable and has been known to crumble beneath millions of people.
Suit up for battle, because this is a war.
We can talk, teach, guide, and instruct, but most of this war is truly on the spiritual level. Most of it will be fought out on our knees. Are you praying for your kids passionately in this area?
As believers we need to enter this battle on the spiritual level. Pray for your sons and daughters that a hedge will be built around them. Pray that the spirit of lust, immorality and perversion will be bound and removed from them. Pray for protection for your house, your family, your mind, your husband. Pray for eyes to see the truth and not turn away from it. Pray for strength and wisdom to see and fight this battle.
Lather, rinse, repeat.
This is not a "one and done" thing. This is a way of life. Talk to your kids and make a deal that anytime you ask how they are doing in the area of purity that they will be completely honest with you. Then be constantly inoculating them. Now is a great time to bring it up, you have an automatic starting place just discussing Josh Duggar or Jared from Subway. (I've never heard if he's a believer, but you can discuss how pornography has ruined his life now too.) A great blog (and internet filter) is Covenant eyes. They have hundreds of great articles on their blog about dealing with porn. http://www.covenanteyes.com/blog/
Don't give up.
If you or anyone in your family has already headed down this slope, don't give up. In Christ we ALWAYS have hope. Find someone to talk to at your church. Or if you don't have a church home or don't feel comfortable going there, you can find great counselors at http://www.biblicalcounseling.com/ or http://www.celebraterecovery.com/