By Jane Sonnenschein · April 15, 2026

1 | We hoped the children would practise Chinese, but they always drifted back to German

When my daughter was younger, I often met up with other mothers from Chinese-German families.

The purpose of these gatherings was quite simple. We all lived in Germany, where our children heard and used German most of the time at nursery, kindergarten, or school. Whenever we managed to get together, the mothers naturally hoped that the children might take the opportunity to speak a little more Chinese.

The families who came were generally very similar. In most cases, the mother was Chinese and the father was German. Occasionally, one or two of the fathers could speak a little Chinese or were trying to learn it, but the overall family structure was much the same.

Yet whenever we gathered, reality quickly overturned that plan.

At the beginning, the children might say a few words or sentences in Chinese. Before long, however, the entire group would almost automatically shift into German.

The reason was not difficult to understand. Many of the children’s Chinese was simply not strong enough to support natural conversation, play, joking, or anything slightly more complicated. Children do not think like adults. They will not deliberately control their language because “the purpose of today’s gathering is to practise Chinese.” They instinctively choose whichever language allows them to communicate most easily.

2 | Many mothers witness the same pattern

Over the years, through one gathering and conversation after another, I began to hear very similar stories from many mothers.

They would often say that their children had spoken Chinese when they were younger. At first, everything seemed to be going reasonably well. Then, without anyone quite knowing why, the children gradually became less willing to use it.

For some children, the change became noticeable at around the age of three. Their mothers would ask questions in Chinese, and the children clearly understood, but they would begin answering automatically in German. For others, it was not until the children were four or five that the parents suddenly became worried. Their child had once seemed to have a real foundation in Chinese, so why was the language now becoming weaker and less present?

In our own family, we never went through a stage in which I spoke Chinese and my daughter insisted on replying only in German. For a long time, I therefore did not fully understand what those mothers were experiencing.

I knew the phenomenon existed, and I had heard many mothers describe it. Yet because it had not happened in my own home, I always felt that there must be something more fundamental at work—something I had not yet properly understood.

3 | “A child can have only one mother tongue” is often a conclusion drawn from reality

Over time, I began to realise that many mothers come to believe that a child can ultimately have only one mother tongue not because they are debating an academic definition.

They reach that conclusion because they have watched their own children grow and witnessed the same process: a language the child once spoke in early childhood is gradually pushed aside by the dominant language of the surrounding environment.

When the child is very young, Chinese may still be present. The child may understand it, speak a little, and manage simple conversations without difficulty. Once kindergarten or school begins, however, German becomes the language used most often, most naturally, and with the least effort. Friends speak German, teachers speak German, books are in German, and games and social life increasingly take place in German as well.

Under those conditions, it is entirely natural for Chinese to move slowly into the background.

At first, the child may simply begin giving shorter answers. Later, their vocabulary no longer keeps pace. After that, they may still understand Chinese but become reluctant to speak it. Eventually, for some children, only the community language continues developing, while their Chinese remains frozen at the level they reached at a much younger age.

When a mother watches this process unfold every day, it is understandable that she would come to a seemingly obvious conclusion: how could a child possibly have two mother tongues when, in the end, only the strongest one remains?

That is why I understand when mothers say that a person can have only one mother tongue. They are not discussing language in the abstract. They are describing the path they have watched their own child take.

4 | The problem may not be that the second language never took root

This is where the real question begins.

When people see the final outcome, they often assume that two mother-tongue systems could never have existed in the first place. Yet the more I have thought about it, the less convinced I am that this is necessarily true.

Sometimes the problem is not that the language never took root. The problem is that the system which had already begun to develop was not maintained.

These two situations may look similar from the outside, but they are fundamentally different.

When a young child receives stable, natural, and sustained input in a language, an early foundation can genuinely form. That language does not simply fail to exist. The difficulty often comes later: as the language of the surrounding environment becomes stronger, does the weaker family language continue to hold the same place in the child’s everyday life?

5 | Whether a language survives depends on the place it holds

That “place” is especially important.

It does not mean speaking a few sentences of Chinese at home from time to time, or remembering at the weekend that the child should practise. It is closer to a stable, long-term role within the family.

For example, the mother consistently speaks Chinese, the father consistently uses another language, and German belongs to school and the wider environment. Each language is connected to particular people and particular relationships.

When this structure remains stable over time, the child’s mind is more likely to develop clear and reliable pathways for each language. But when the family shifts constantly between Chinese and German, translates whenever the child might not understand, and sometimes gives up because using German feels easier, the child will naturally choose the strongest and least demanding language.

What many parents later interpret as proof that “a child can have only one mother tongue” may not be an inborn limitation at all. It may simply mean that, in the long competition between languages, the language of the wider environment won.

6 | Many people debate definitions; I care more about how the outcome is produced

This is why I increasingly feel that the claim that “only one mother tongue remains in the end” is often not really a question of definition. It is a question of outcome.

When a language is used less and less in everyday life and receives fewer opportunities to grow, it will naturally fall behind. Parents then look at the result and conclude that a person must have been capable of only one mother tongue from the beginning.

From another perspective, however, a more accurate explanation might be this: it is not that a child is naturally limited to one mother tongue, but that the weaker language is extremely easy to lose during the process of growing up.

7 | What matters may not be whether it “counts” as a mother tongue

This is also why, in recent years, I have become less interested in the question of how mother tongue should be defined and more concerned with another, more practical question: why do so many children who once spoke Chinese quite well begin to lose it little by little?

When does the decline begin?

Why are some families able to preserve the language while others are not? If a language system had already begun developing in the child’s mind, why does it later become weaker and weaker?

These questions may be more important than whether a language officially “counts” as a mother tongue.

For many families living in Germany—or in any country where the language of the wider environment is overwhelmingly dominant—the real source of anxiety has never been an abstract definition. It is the experience of watching a language their child once possessed gradually retreat and not knowing how to bring it forward again.

8 | It is not that children cannot learn it; the language loses its place first

Perhaps this is why so many mothers eventually say that a person can have only one mother tongue. They are not trying to make a linguistic judgement. They have simply watched their child arrive at that outcome.

Yet I increasingly believe that this result is not the only possible ending. It is better understood as a position—a position that can be protected, but can also gradually be lost.

Many children are not incapable of learning Chinese. Rather, in the long competition between Chinese and the dominant language around them, Chinese is the first to lose its place.

When mothers conclude that “a child can have only one mother tongue,” I now see that statement less as a starting point than as the description of a result. The more important question is how that result takes shape, step by step.

That is what I will continue to explore in the articles that follow.

This essay is also available in other languages:

Chinese version: 为什么很多宝妈最后都会觉得：母语只能有一种？

German version: Warum glauben so viele Mütter am Ende, dass ein Kind nur eine Muttersprache haben kann?