My wife and I have raised our son bilingual. There are various approaches to raising children bilingual, but the method which is often reported to get the best results is "one-parent-one-language" (OPOL). As such, since the birth of our son (actually even before he was born), we have followed a strict system in which I only speak Japanese with him, whereas my wife only speaks English.

It can be scary at first as a family trying to raise children bilingually. You may have many worries and doubts. What if my child rejects the minority language? What if my child mixes up languages? What if he doesn't learn either language to a native level?

Fortunately, it didn't take too long before most of our fears were dispelled. Before his third birthday, it was already clear that he spoke and understood both languages without ever mixing them up.

I was most amazed when he was around this age and I was speaking with him in Japanese when his mother asked, "What did papa just say?" Without hesitation he turned and gave her a perfect idiomatic translation into English. This was surprising to me because the phraseology and organization in Japanese and English is completely different. A one or two word phrase in Japanese may require five words in English. What we say in Japanese with an adjective may be expressed in English with a verb. As a result, translating things word for word between these two languages will essentially never be correct.

And yet, our son could translate effortlessly between English and Japanese at two years of age with zero meta-linguistic awareness and zero understanding of the complexities suggested above.

This got me thinking: maybe human brains were made to be multilingual from the beginning. In other words, multilingualism isn't just a special feat that we can trick our brains into doing -- they were designed for multilingualism.