Bilingual Children

At an American friend's party last weekend, I met a British guy, then his clearly American wife – then heard the two of them speaking both German and English to their two kids, ages 4 and 5.

Wait, I thought, but which of them is the German native speaker?

The "usual" way to raise bilingual kids would be for each parent to speak their own native language to the child, who grows up understanding both. Or, you might have two speakers of one language raising a child in a country that uses a different language, in which case the child also grows up with both languages. But two English native speakers using German with their children?

I asked them about it, and they explained that they used to use only English with the kids – understandably, since they're both native speakers – until the preschool here in Berlin told them their sons were falling behind on their language skills, understanding German but not speaking it.

So the parents developed a new plan: English at home (inside the car also counts) and German everywhere else. They said it works great (they're both very good at German, and have of course gotten even better now that they have to think fast enough to reprimand their children in it!) and the boys will even correct them if they forget and slip into English in public.

Some people were pushing them to use only German, the mother said, but what kind of sense would that make, when the rest of the world is desperate to learn better English, and they can give their kids the gift of speaking it from the start? (And what sense does it make for a person not to be able to speak their own language with their children?)