How easy would it be to define dogs as four-legged animals?
Yet there are three-legged dogs. Many. Some people have never seen them. I knew one personally, and have seen three others closely.
My children learned to read without being taught.
If my children were the only children in the history of the world who learned without being taught, it would still be a fact that some children have learned to read without lessons—that a child can learn to read without lessons.
But my children are not the only ones. There are many. There were many even before schools existed, though it was harder without being surrounded by talking video games and movies with subtitles and printed boxes all over the kitchen, and signs on every street and building and shelf.
(The quote is from this topic, about 4/5 of the way down.)
photo by Sara McGrath