Children and Internet pornography
Children today grow up in a far different sexual world than older readers of this wiki did. No more world in which Penthouse is the strongest porn you can get. Children today are surrounded by hard-core sex, including parents who deliberately don't conceal their fucking from their children. With the near-universality of the Internet, and the constant decrease in the cost of storage, porn has become abundant. Anyone with a computer connected to the Internet has access to all the porn one could want. It's anything but hard to find. The problem may be keeping it away.
Even in the most conservative household it is all but impossible to keep kids who want it from enjoying porn. First, because the dad in the household may love porn (even though he cannot be open about it), and does all he can to reign in his wife. Secondly, because while it is possible to keep pornography out of the home - no computer, no cable TV, no cell phone pretty much takes care of that - the boy (or girl), unless home-schooled, also goes out of the home. He can see porn at a friend's house, on a school computer, at the public library. (Librarians in general are very pro-First Amendment and as a result porn-friendly.) He would hear about porn from one of the many articles about it (Internet porn) found in mainstream magazines and newspaper, the sort of things one finds, in the U.S., at a high school library.
Children also have much more access to sexual information. Sexual information abounds on the Internet, specific to whatever age, gender, or ethnic group one wishes.