How much of sexual behavior is instinctual?

Is there ‘instinctive’ or ‘unlearned’ sexual behavior (other than masturbation) in humans?

My youngest brother has been diagnosed with ‘autistic like’ behavior. He parrots but does not converse (for example, he will say lines from Transformers, the movie at odd times). He will respond to ‘no’ but does not seem to understand more complex communication. He is much younger than I am, and I only see him when I visit with our parents. He is 14.

Recently, during a visit, he put his hand on one of my breasts. When I realized that it wasn’t an accidental touch, I removed his hand, told him no, and he wandered away. I mentioned it to our parents, and their reaction was that it would not have been a sexual touch, that such behavior is learned, and he has had no opportunity to learn it.

I disagree, but I’ve also read that body parts that are considered attractive vary from culture to culture, and that touching breasts is not necessarily a sexual act.

Any cites would be much appreciated.

I, too, have often wondered: If a group of infants are isolated and never taught anything about sex or reproduction, will they eventually “figure it out” by trial and error as they develop into adults?

I’m far from being an expert, but I’ll give it a shot.

I do not believe it was done with instinctual sexual intentions.

IIRC, humans and some other animal (dolphins I beleive) are the only animals that have sex for pleasure and breasts, being as fun as they are during sex, are not nessesary during the act of ‘love making’. (I have yet to see a show on the discovery channel of a couple of chimps in the act and the male chimp going for a ‘reach around’.)

So with that being said, the chances of it being instintualy sexual as nil (IMHO).

There are two possibilities for this occurance though.

1.) He’s picked up what most men know…breasts are sexually appealing and therefore it was done in a sexual manner. (You said that"…and he has had no opportunity to learn it…" but I’m sure my parents thought the same thing…you’d be surprised what people can pick up…all it takes is flick of a channel in some cases…)

But don’t think of it in the same sence as you would any other man doing it. You said he was 14, so his pubesent hormones and his ‘autistim’ could just have gotten the better of him.

or

2.) He may have just noticed something different on you. Some thing he doesn’t have and was checking them out. You being his sister may have made him more comfortable with using you for his ‘experiment’.

(I’m leaning more to #1)

Either way, I think your parents are wrong. He’s picked it up from somewhere…he just needs to be told its wrong.