A woman whom no one has seen for 19 years who was "lost" in the jungles of northeastern Cambodia when she was 8 years old has appeared and "her father" has popped up to claim her. This woman is unable to speak intelligibly. When hungry she rubs her stomach. it seems. She can't say the Cambodian equivalent of "I am hungry."
A question that will inevitably come up is whether this woman will ever be able to speak the language of Cambodia (officially "Khmer"). The answer is "No." One might think that since she was "lost" at the age of 8 she might be able to recover her language skills. If, in fact, she is a reasonably intelligent person and she had an 8 year old's command of Khmer, that would be possible in principle. The problem is that with "feral children," the term I have seen most often in the linguistic literature, we find that the children tend to be mentally retarded and that is why they came to be "lost" in the first place.
DNA tests have not yet been done but apparently will be so we don't yet know for sure whether the father is her biological father. That this man came forward could mean that he genuinely wants the child back. But there are other possibilities.
Feral children are always of interest. The most famous American case involved Genie, a child who was diagnosed at around the age of 6 or 7, after she began to learn language, as mentally retarded. Her mentally ill father decided that "to protect her" he would pen her up, tying her down in a sitting position on a "potty chair" wearing diapers and enclosing her in a sleeping bag in a crib she couldn't escape from at night. He beat her if she attempted to vocalize and would bark at her to scare her if she displeased him. When she was found at age 13, there was a great deal of scientific interest in her but after it was learned that nothing was being learned from studying her, federal funding for the research was cut off and the scientists lost interest. She was passed around from foster home to foster home, never becoming socialized or learning language. Of course her early beatings for attempting to vocalize could have had something to do with that.
In 1964, the linguist Eric Lenneberg became quite famous for proposing that there is a critical age of language learning that runs up to about 12 years old. He argued that while one may become a fluent speaker of a language as an adult, one will never acquire the full abilities of a "native speaker." This is one of the underpinnings of nativistic theories of language learning and of language competence of the sort Chomsky has proposed. So far as I know, no one has ever refuted Lenneberg's thesis. By a "native speaker competence" I mean someone who speaks without a foreign accent, can judge whether or not a sentence is or is not "grammatical" with a very high level of success (I mean a sentence any native speaker of that language would accept as well-formed) and, at least in some cases, has a knee jerk negative response to most dirty talk and other taboo expressions. The Pavlovian conditioning as a child to think that such English expressions are "bad" does not occur if they learn English as an adult.
I have had personal anecdotal experience that Lenneberg's thesis applies not just to learning a new language but also to adopting a new accent of one's own language. English speaking actor's clearly have the ability to adopt accentless American or British or whatever English is required. Indeed, the US has been flooded with an amazing array of "down under" actors who most of us probably think are American including such Aussies as Nicole Kidman, Naomi Watts, and Hugh Jackman, and a legion of others) or South Africans like Charlize Theron and Thomas Jane etc. When the movie Briget Jones' Diary came out in film, the American actress, Renée Zellweger, was said to have had too perfect a version of standard British English. I have been shocked on seeing interviews with foreign actors who speak in unaccented English in movies (or the correct American dialect for the role) to hear Aussie or British or South African English come out of their mouths. We have been invaded by the Commonwealth nations.