" At birth, your baby can distinguish between the sounds of every language that has ever been invented. Professor Patricia Kuhl, co-director of the Institute for Learning and Brain Sciences at the University of Washington, discovered this phenomenon.

She calls kids at this age “citizens of the world”. Chomsky puts it this way: We are not born with the capacity to speak a specific language. We are born with the capacity to speak any language.

Unfortunately, things don’t stay that way. By their first birthday, Kuhl found, babies can no longer distinguish between the sounds of every language on the planet. They can distinguish only between those to which they have been exposed in the past six months.

A Japanese baby not exposed to “rake” and “lake” during her second six months of life cannot distinguish between those two sounds by the time she is 1 year old. "

― John Medina , Brain Rules for Baby: How to Raise a Smart and Happy Child from Zero to Five