Dutch of course....
For me that's my native language, David was born in South Africa, but also speaks perfect dutch.
but language is a funny thing.
In the past I went abroad a few times with some co-workers.
and about the third day someone will start speaking English to each other without being aware of it.
and the other one automatically replies back in English.
then after 10 minutes or so we say: why do we speak English instead of dutch?
had i a couple of times, real funny right?