>>28595907Well, I'm glad you asked that. The truth is that when you are a child, your brain plasticity is such that it's able to learn pretty much anything, language-wise. From your parents and anyone else around you speaking language you acquire everything having to do with the basic functions of your language, including all of the phonemes your language uses, your accent, and your basic vocabulary. As you get older, your brain essentially gets firmer and it becomes harder to learn language, and that includes things like accents, and pronunciation of unfamiliar phonemes.
Japanese children grow up surrounded by the Japanese language which actually has neither the "L" or the "R" phonemes. They actually have a third, similar phoneme which sounds to our English-speaking ears more like an R than an L, but it's actually shaped very differently in your mouth.
R as in "Rake": [r]
L as in "Lake": [l]
R as in "Roku": [ɽ]
So the actual question is why don't we as English-speakers, have the [ɽ] phoneme, and the answer is the same reason Japanese-speakers don't have the [r] or [l] phonemes.
