It does depend on what we mean by read and write. I don't mean just recognizing letters and being able to reproduce them. An adult should be able to read and un

It does depend on what we mean by read and write. I don't mean just recognizing letters and being able to reproduce them. An adult should be able to read and understand an article from a decent newspaper (say the Financial Times), and write a 5 line summary. Definitely not all 12 year olds can to do that and, I'd argue, a large fraction of adults can't either.