I'm very sorry to say this, because it's just one more thing that makes us abnormal in comparison to NT peers, but here goes.
As I've grown older, I've come to believe that my Baptist grandma and my paternal relatives' "You're stupid, don't try" approach to me kept me out of a lot of trouble (well, except for my cousin's using the fact that I knew I had to buy friends if I wanted any to get cigarettes, alcohol, and pot).
I did not try to date. I went out one time with one boy; he tried to stick his hand down my pants. I let him-- and then I made sure I was never alone with him ever, ever again. Once I got rid of him, I wore baggy jeans, baggy t-shirts, and baggy flannels-- through the next 3 years of high school, only one other guy ever looked at me twice, and that one fell in love with my mechanical skills and sense of humor, and was respectful when I said, "I don't date."
Porn was dirty and wrong. I did not look at porn.
Now, I realize that I had some trauma and no sex drive. But how hard is it to teach a kid, if they must look at pornography, to stick to magazines that are available at the local gas station?? It's black-and-white. It costs money, means they have to leave the house and be seen buying a copy of Playboy, Penthouse, or Hustler, and means they are going to be completely left out of the Internet porn discussed by peers...
...but it's cheaper than a lawyer, perfectly well-respected "normal" people are seen buying those mags every day (DH has a subscription to Playboy; the mail lady asks me if I've read such-and-such article and usually I have), and the fact is that autie kids and young adults (and old adults, too, for that matter) are going to spend most of their lives being left out. The sooner we make peace with that, the better.
There were a lot of other things I did not do, for fear that I might get in trouble. I did not explore science and chemistry beyond the experiments we were given in school. I wanted to, but by the time I was old enough to be curious I was also terrifed of the trouble I would get in if I, say, left a burn mark on the counter playing with paper towels, mayonnaise jars, and isopropyl alcohol (which can also be considered a crude Molotov cocktail, and get you put in jail if the fire department gets called). I probably would have been perfectly safe attempting such things in the wide gravel driveway of my Dad's extremely rural property...
...but by the time I was old enough to be left home alone, I was too terrified of the risks to try.
OK, I could have been a great chemist. Maybe I'd have come up with the successor to flat-film solar panels, or invented Heelys 10 years sooner (had that idea as a kid), or figured out a cheap way to separate sea water from salt (something we're definitely gonna need if we're not going to end up feeling like we woke up one morning on Arrakis). More likely, though, is that I would have ended up a felon, whether I meant any harm or not.
The solution to the porn problem, as well as so many of the other messes HFA kids and young adults get themselves into, is to teach JUST DON'T.
It's not pleasant. As parents, you don't feel good doing it. You know that you are stifling creativity, ruining whatever great things they might do someday, teaching the child to live in fear. And you ARE doing those things.
But-- felons don't get much of a chance to find constructive outlets for creativity. I'd rather live in fear than live in prison. My life may be a sad, boxed-in, frustrated story of truncated goals and unrealized potential...
...but there are no felony charges in my story, either. I haven't made the news in good ways or bad, and I won't be remembered after I'm gone.
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"Alas, our dried voices when we whisper together are quiet and meaningless, as wind in dry grass, or rats' feet over broken glass in our dry cellar." --TS Eliot, "The Hollow Men"