I knew a guy once that moved to the United States with his mom when he was 14. Neither of them knew English at all at the time. When he started going to a public school and started working at a store in town, he was able to get a grasp on the language. Fast forward a few years to when I knew him, and he was able to speak really well. You could tell that he was still learning, there were words he didn’t know and a lot that he pronounced badly. But, all things considered, he spoke very well.
His mom was a different situation. She was a stay at home mom, and she focused on her son, and later her younger son. She spoke in fragmented sentences and I found that when I was around her I would talk like that too. Her younger son was born in the US and he did not have the Russian accent that his older brother had, and he often seemed to have a toggle switch in his head. He would say a few words in English and suddenly switch back to Russian.
I was always impressed by the difference between them. When I first met them I had no idea what they were saying, I was not able to find breaks in words, sentences, even thoughts! But as time went on, I was able to pick up on cues and I could hear words repeated and I started to pick up on the sounds I was hearing.
This, of course, led me to want to learn Russian. I had always wanted to learn something fun. I dabbled in German and French throughout high school and my time at Penn State, I wanted to change things up. I started trying to write the words and speak them. I was apparently not good. His mother often giggled at things I would say and he would too. His little brother would try to help. I found that I was speaking Russian the way she spoke English.
Why was it so hard? Well around 9-12 months of age babies start to lose the ability to distinguish sounds that are not in their native language (Sohn 2012). From there it is all down hill (for lack of better words). According to the same article written by Emily Sohn, after puberty there will always be an accent when speaking. Her article really made sense of why the three of them were so different. Yelena was in her 30’s trying to learn a new language, Andrey was 14, and his little brother Leo was born learning both at the same time. It isn’t impossible to learn a new language, but as we go through the years, it becomes more and more difficult to get the concepts of other languages. There are often times that I am still learning how the English language works.
http://news.discovery.com/human/psychology/brain-language-learning-1203191.htm