People who are adopted as babies do not forget their native language. Recent research by Radboud University, among others, shows that Korean adoptees learn Korean more easily at a later age. Even if they were only a few months old at adoption.
Language learning begins in the womb. In the last term of pregnancy, when hearing is fully developed, the fetus already hears its mother talking endlessly. The baby is especially sensitive to the rhythm of his mother tongue and recognizes it immediately after birth. A child only really starts experimenting with sound sequences such as dadadada when he is six months old, in the so-called babbling phase. Until then, listening is key.
This knowledge that a baby gains in the first months of its life is never lost. Mirjam Broersma of the Center for Language Studies in Nijmegen discovered this when she introduced 29 Korean adoptees in the Netherlands to their mother tongue. Together with colleagues from Australia and Korea, she published her results in Royal Society Open Science.
Subtle sound differences
With the exception of the control group, the participants in Broersma's study were born in Korea. They were adopted at a very young age by Dutch-speaking parents. Half of them were younger than six months at the time of adoption, the other half were older than seventeen months (but younger than six years). During the study, the participants were between 23 and 41 years old. The people in the control group were born and raised Dutch people of about the same age as the people in the adoption group. They were also comparable in other respects, such as educational level and number of times they had visited Korea.