Crazy - I think the problem with children watching porn is the same problem is that it warps their view of what the real thing should be like, only it is more severe as the average 12 year old has not had sex and has no experience in sexual matters with other people. What porn does to children is it often makes them believe that women should be treated the way they are in pornos in real life, which can lead to kids being disrespectful and degrading to women who they may be having sex with. To me, if you happen to be 17 and emotionally mature enough to realize that its a movie and not reality, and you feel like watching some porn, then thats ok, (porn laws are you have to be 18 to watch it where I live, not sure about other areas) but the problem arises when a younger guy or girl watches porn without realizing that it isn't the only way to have sex, and they are influenced by it either by treating women poorly during sex, or if the girl sees it and gets disgusted by how the women are treated and wants no part of it, she may become wary of sex because of how she thinks she would be treated.
That's obviously all speculation, as I've never known a girl under 16 to watch porn, so maybe its all a load of shit, some of the ladies on here will have to comment.