Parents sometimes worry that bringing up their children as bilingual will mean that they never really master what should be their native language. Research shows this is just not true.
To quote from “The Local,” a Swiss online paper, “Research shows that children can learn to read in two languages at the same time, to the benefit of performance in both languages. Bilingually educated children are shown to read at a higher level than children educated in only language.  Bilingualism does more than refine children’s linguistic abilities – it also improves their cognitive abilities. In other words, it makes them brainier.”