It IS autism where the kids allegedly cannot lie. And this is true, to a certain extent. But we all have different definitions of what is a lie. Plus, you have to consider the definition of "lie" from the child's point of view to see where it fits in.
difficult child 3 CAN lie, but he can't invent a complex alternate reality. So when challenged by a teacher he would say, "I didn't do it," when he later admitted he DID do it, but he couldn't say, "I didn't do it because I wasn't there, I had been called up to the principal's office to do a job for the principal, I don't know what happened because I was doing a task for Mr J." Unless, of course, it was true.
difficult child 1 would try to lie also, but would make a hash of it. Both boys try to lie (although I think they're giving it up now, because I keep catching them out) but they are so BAD at it.
There ARE times when one of my difficult children will tell me something complex which I know is not true. When I discuss it with them it turns out that they BELIEVE it to be true. Example: difficult child 1 says, "I'm not washing up tonight - I washed up last night!"
When we think about it, ask around, there is no way difficult child 1 could have washed up last night because he wasn't home for dinner. BUT we do find that difficult child 1 DID wash up the last night he was home. So what he remembered was what he claimed to be true - because he genuinely believed it to be true. This is not a lie, although some people would call it one.
Another variation on this is when a difficult child WANTS a particular answer to be true, to such an extent that he convinces himself. Whenever we remember something we are actually rewriting that memory into our heads. So if a child mentally confuses what he wants to remember with what he SHOULD remember, you will get what appears to be lying. However, this tends to involve more creative thinking than you find commonly in autism - but you might find it in the highest functioning autistic kids.
Also, they can LEARN how to lie effectively. difficult child 3 was sending an email to his aunt, thanking her for a birthday present which I KNOW he was rather underwhelmed with. He was enthusiastic about it in his email, thanking her and saying it was just what he wanted. It looked very much lie the standard email you would send to someone - you NEVER say what you really thought, if it was something you didn't really want. And difficult child 3 seems to have mastered the art of lying to be polite. Sometimes, anyway. Drafting an email gave him time to choose his words, which is why I think he was able to do it.
So we live in a world where we HAVE to be able to lie, to a certain extent. Every bloke, when he has to deal with the women in his life, has to be able to survive answering the question, "Does my back end look big in this?"
For males especially, lying is a survival need.
Marg