studies show that if a child is left in isolation with no emotion places upon them up until they hit puberty then they withhold no chance of picking up speech because they're brain pattern has already adapted to what it has learnt. as teenagers our brain is reprogramming itself every minute because it is growing and adapting to its 'character' so to speak. as you know a lot of teenagers rebel against parents and slam their doors,this is actually (believe it or not) a healthy stage of upbringing because it shows they're brains becoming its own character and adapting to itself based on what it has learnt. this is why teenagers argue with parents,because they develop their own self character instead of being dependent and innocent as a child,relying on parents opinions. is that good enough for you?:L my mum is doing psychology at her college and i kind of learnt this off her and read through some of her studies:) probably doesn't totally make sense but meh