Research suggests that bilingual children have improved thinking abilities, better attention spans and self-control. It appears that being able to switch from one language to another develops the part of the brain involved in controlling our attention and emotions.
Therefore, if you are a bilingual family, it is a good idea to start teaching your children a second language straight away.
The most common method is one Person, one Language (OPOL). For instance, the dad might speak his native Dutch, while the mum speaks English. However, there are other methods such as only speaking the minority language at home. The important thing is to be consistent.
Judith offers some tips for encouraging bilingualism in children on her blog: http://sixtineetvictoire.com/10-tips-to-encourage-bilingualism-in-children/
So should we all be teaching our children a second language from a young age?
In my opinion, this is probably very difficult unless we are a bilingual family. There is a myth that younger children are more skilled at learning a second language. A study of 17,000 British children learning French at school, found that children who learnt French from 11-years-old performed better on tests that children who had begun at 8-years-old (Stern, Burstall and Harley, 1975). Another study looked at French immersion programmes in Canada found children who learnt French at 11-years-old performed just as well or better than those who began at 5-years-old (Genesee, 1981, 1987). The immersion programmes involved teaching English-speaking children lessons entirely in French.
This relates to the problem of children coming to England from other countries being immersed in an English education system when they hardly speak any English. Some teachers believe that these children will easily pick up English but as the research shows this is not the case. Children who do not speak English as their first language will need explicit instruction and their first language should be used as a bridge to support learning of English. (Barry McLaughling, 1992).