Re: Autism and sexuality
With the syndrome, I believe, repetitions are frequently formed, so this could become a habit, if not already. I would advise that you do not stress to him, elaborating on the topic, but be very wary of what he has access to (for example: restricted websites) and when he does approach the topic, talk him through the precautions neccessery. Do you openly talk about sex? If not at this age, would you feel comfortable doing so with him in future, or would you feel embarassed? Do you feel confident that you could approach his teacher about it?
Also, make sure you know of his friends, their reputation, and influences. Peer pressure and genuine curiosity would definately dominate here if not investigated.
I hope I might have helped in some way! x