The same thing happened with Attention Deficit Disorder (ADD) and Attention Deficit Hyperactivity Disorder (ADHD). I'm a retired teacher. When I started teaching in 1971, autism and ADD were unheard of. As far as late-speaking children are concerned, my husband was born in 1944. Back then, men would drive horse-drawn carts up and down the streets, yelling that they wanted old rags. When my husband was 4 and had not yet uttered a word, he went out to the porch when the "rag sheeny" was going by. His mother heard him say "old rags" and he hasn't shut up since. He also has a masters degree in math.