There’s no doubt that speaking multiple languages is a great advantage. I grew up bilingual myself, speaking Spanish and German. I am very grateful now that I got that extra language without much effort. But I met a lot of people with parents who spoke different languages who still only learned one language, usually the one spoken in the country they were raised. So it’s not always self-evident that a child will learn both parents’ languages.
As I knew I wanted to raise my son bilingual, I did some research to make sure I had the necessary information and the right basis to make it happen. I found out that usually, there are two main reasons why parents don’t teach their children their (foreign) mother tongue: they fear that their child will end up speaking two languages but neither of them perfectly well, as they will confuse one with the other and never focus completely on one. In my own experience, that doesn’t have to happen. I spoke Spanish at home with my mother, but learned and spoke German at school and with all my friends. German became my first language. My Spanish isn’t perfect, but I speak it fluently and it didn’t only give me the advantage of that second language, but also made it more easy to learn other foreign languages.
On the other hand, what often happens, is that a parent first starts talking to their child in their mother language but at some point switches because it’s easier for the child. The most important rule for success that I found is: be consequent! If you start talking to your child in their first language , he or she will be happy to use that language, as it’s easier than learning and speaking a different language. When I was about 8 years old, I didn’t want to speak Spanish to my mother anymore. I wanted to be just like the other kids, speaking German. This lasted more than a year, but my mother refused to talk back to me in German. So I talked German and got answers in Spanish. I am thankful for that now I can tell you!
Up to now, I have managed to stay consequent and only speak German with Henrik. It can feel awkward sometimes, for instance in front of people who don’t know a word I am saying. But I never switch because I know it will be worth the effort. It is working well so far, he is 2,5 years old now and switches between German with me and Dutch with his father and our Dutch friends well. Dutch will be his first language, as he just hears and speaks it way more often. But I don’t aim at perfection. If he can one day communicate ok in German and make use of that advantage, I have reached my goal.