Having "the talk"

I've been trying for some time to think about how, when, and whether to talk to my son, now 12, about sex. On the one hand, he's probably past the age at which he should know the nuts and bolts about the birds and the bees. On the other hand, giving his impulsivity and tendency to perseverate on words and phrases, I'm afraid he might share any information given to every stranger he meets, or maybe shout it out in the cafeteria. Is no news good news? The authors of Sexuality: Your Sons and Daughters with Intellectual Disabilities say no: You've got to tell, and you've got to tell now. Children with special needs are extremely vulnerable to abuse, and all the more so if they're ignorant of the way things are supposed to work. The book spends a lot of time dealing with the need to give intellectually challenged kids satisfying, full lives, and not as much dealing with problems like my cafeteria nightmare, but it's still interesting reading for parents who are trying to figure out how our kids will fit in the real world, and how we can best get them there.