But im not saying that cuz, I'm saying that you must have learnt it to know it. And yes, you can still teach someone more on Turkish if they were born in Turkey. For example, What if they didn't go to school?. They might know how to communicate but at what extent?. They would be able to speak but using proper language? There are many reasons where a person in the case you have given will be unable to talk the proper language. Spelling Writing Reading... these are all to do with "learning". Of course you can speak but how? because you've learned it. Simple cuz S i m p l e