Mr. Paul raised this topic earlier. We must not forget that some people are dissuaded from answering the question on mother tongue. There is a question, but it is imperfect. As Mr. Paul said, the instructions clearly say that if you learned two languages at the same time and spoke one less often than the other, you must choose only one of those languages. In fact, it is asking people to provide false information.
I think that on that topic we would like it to be clearer.