>However there's now significant research showing to not do that. Here in Sweden immigrant parents are actively encouraged to speak their mother tongue at home

>However there's now significant research showing to not do that. Here in Sweden immigrant parents are actively encouraged to speak their mother tongue at home and not try to help their children by speaking Swedish, because it's counterproductive. Won't this cause the situation Estonia has with the Russian-speaking minority? Enough immigrants banded together to create Russian-speaking communities. Many of them never learned any Estonian as a result, because they didn't feel they needed to. Most people in stores spoke Russian, they put their kids into a Russian speaking school etc. The end result is that there are many people in Estonia that have lived here almost their entire lives, but cannot speak Estonian at all. This makes their lives more difficult: from finding a job to getting a better education to dealing with bureaucracy. Even if you send your kids to an Estonian speaking school it causes issues. They'll suffer academically - imagine doing school effectively in a foreign language. It would make a kid want to go to school even less. In that case you're effectively handicapping their future. I'm not sure that some minor cognitive advantages are worth the risk of not assimilating.