Sgt Bowe Bergdahl spoke English for 23 years until he was captured by Taliban fighters in Afghanistan five years ago. But since his release, he has trouble speaking it, says his father. How can you lose your native language, asks Taylor Kate Brown. Some people have gone decades without speaking or hearing their first language but they retain the ability to speak it easily, says Dr Monika Schmid, a linguistics professor at the University of Essex in the UK. But others begin losing fluency within a few years of not speaking it. It's rare to totally lose command of a...