As a parent on the spectrum with 2 young sons on the spectrum, I just realized that I have always made it a point to be very literal in my speaking/teaching, even before I knew they were on the spectrum and before I knew I was on the spectrum. For example, I hardly ever use the standard "colorful" figures of speech, as I figured it would confuse little kids to say them. But once in a while I'll say, "Look at that rain! Some people might say it's raining cats and dogs, but that doesn't really mean cats and dogs are falling out of the sky--It's just a figure of speech meaning that it's raining really hard." I never just say to them, "Look, it's raining cats and dogs!"
When I write poetry though, that is an entirely different matter and I get VERY colorful!
I wonder if NT parents do this when they speak to their kids?