— A Debate in the Comments Made Me Rethink the Idea of Having Two Mother Tongues

By Jane Sonnenschein · April 14, 2026

1 | One Comment Stopped Me in My Tracks

A few days ago, while scrolling through Xiaohongshu¹, I found myself debating with another mother in the comments.

She said that a person could have only one mother tongue, just as a person could have only one mother.

For a moment, I did not know how to respond. Her statement sounded almost like common sense, yet something about it did not feel quite right to me.

The post was about multilingual children and how families living abroad could help their children maintain their Chinese. One mother in the comments asked whether a child’s Chinese could ever reach the level of a mother tongue.

I replied almost without thinking: yes.

If each parent consistently maintains their own language role within the family, and the child grows up receiving stable, natural input from an early age, it is possible for that child to develop mother-tongue-level proficiency in more than one language.

I did not say this because I was imagining an ideal situation.

I said it because, after watching my own daughter grow over the past several years, I have become increasingly aware that the language experience of a multilingual child is fundamentally different from that of an adult who later learns several foreign languages.

2 | Some Language Switching Is Not Translation

My daughter moves between languages very naturally in different situations.

She speaks Chinese with me, English or German with her father, and enters yet another language environment at school.

It does not seem as though she first thinks in one language and then translates the thought into another. It feels more as though she naturally activates a different system of expression according to the person and the situation.

Of course, she is still growing, and I do not want to make claims that are too absolute.

But I increasingly struggle to believe that a child’s other language must automatically remain at the level of merely “a very good foreign language.”

The mother in the comments disagreed.

She believed that every person could have only one mother tongue. In the best possible case, she said, Chinese might become a well-spoken foreign language, but it could never truly be the same as a mother tongue.

We went back and forth for several comments.

Only later did I realize that we were not really arguing about a single word. We were touching on something many multilingual families easily overlook:

When parents begin with the assumption that a child can have only one mother tongue, the other language is very likely to be mentally downgraded to the status of “a fairly good foreign language.”

And that assumption directly affects everything that follows: how consistently the parents maintain the language, how much input they provide, and how firmly they protect its place within family life.

3 | It Looks Effortless Online, but Real Life Is Not So Simple

Before that discussion, I had never examined the question quite so seriously.

Part of the reason was that our daughter’s three languages had always developed in a relatively balanced way.

Her relationship with Chinese is particularly noticeable. Whenever I am present, she switches to Chinese almost immediately.

This is not the kind of switching where she pauses to think about which language to use. It is more like an automatic response.

Even when her classmates or teachers are standing nearby, her first instinct is often still to speak Chinese whenever she is talking directly to me.

We have reminded her before that, when other people are part of the situation, it is often better to use a language everyone can understand.

But she has already developed a very natural response pattern: when she turns to me, Chinese simply comes out.

This has stayed with me partly because she usually listens carefully to her father and takes rules and consequences seriously. Her father has become angry about this on several occasions.

Yet even that has not easily changed her language response.

In a way, this is precisely what shows that Chinese is no longer a choice she has to consider. It is something she accesses directly and naturally.

Because of this, I used to assume that children growing up with two or three languages in a multilingual family would naturally develop this way.

The more content of this kind I saw on Xiaohongshu, the easier it became to form the impression that multilingual children simply grow up speaking all their family languages effortlessly.

But over time, I began to understand that everyday reality does not look like the version we often see online.

I have met many children from Chinese-German families. Some can barely speak Chinese, while others speak it only with considerable difficulty. There are even families in which the German father speaks Chinese, yet the child still struggles to express themselves in it.

Children from families in which both parents are Chinese often have an early advantage, because Chinese is the shared language of the household.

But that does not mean their Chinese will automatically remain secure.

As children grow older, their Chinese can gradually begin to loosen if their parents do not continue guiding and supporting it consciously.

Some children can still speak Chinese, but their sense of the language begins to sound slightly unnatural. In other families, siblings gradually start speaking German with each other because it feels easier and more automatic.

Over the years, I began noticing these patterns one by one.

It was only after that debate in the comments that I seriously asked myself for the first time:

Can a person truly have only one mother tongue, or have we simply understood the idea of a “mother tongue” too narrowly?

4 | What Is a Mother Tongue? One Sentence from My Husband Made It Click

Later, I discussed the question with my husband.

English and German are both mother tongues for him.

He said that the feeling of a mother tongue is actually very simple. It is like opening a drawer: when you need a particular language, you simply pull open that drawer.

There is no translation and no transitional stage. You do not first think the thought through in another language.

What he said had a powerful effect on me.

I speak three languages myself, but I know very clearly that only Chinese is my mother tongue.

However fluent I become in the other two languages, there is still a certain sense of conversion in my mind when I use them.

Most people who have learned a foreign language will recognize this feeling.

When we first begin learning another language, we often do not think directly in it. We first form the meaning in our mother tongue and then translate it into the target language, such as English or German.

As we use the language more often and become more proficient, that sense of translation gradually becomes less noticeable.

Many simple expressions begin to come out directly, without first passing through the mother tongue.

But as soon as we encounter an unfamiliar word, or try to express something more complex or subtle, the feeling of translation often returns immediately.

In other words, however fluent a foreign language becomes, it may still carry traces of having travelled there from the mother tongue.

A mother-tongue-like process is often different.

It does not begin with one language and then move into another. It is more like accessing the meaning directly, before language has been consciously selected.

That was when I suddenly understood something:

Many people instinctively believe that two mother tongues cannot exist, not because such a state is impossible, but because they have never personally experienced a language that does not involve this feeling of translation.

5 | From Translating Words to Conveying Meaning

During my student years, when I worked as an extra at a U.S. military base in Germany, I also encountered many interpreters.

Some worked in a very typical “foreign-language mode.” One person would say a sentence, and the interpreter would render that sentence into the other language. Their working unit seemed to be the individual word or sentence.

At its core, this was still a process of replacing one set of language with another.

My husband has also worked as a simultaneous interpreter between English and German.

When he interpreted, he did not usually translate one sentence word for word into the next. Instead, he would listen to an entire passage, absorb its meaning, and then produce a complete expression in the other language.

It was not language being transferred into language.

It was meaning being transferred into meaning.

These two processes are very different.

The first resembles the way a foreign language is often used. The second comes closer to the way a mother-tongue system operates.

This is why I increasingly feel that the question “Can a person have only one mother tongue?” is not really an argument about linguistic ability.

It is an argument about what we mean by the term “mother tongue.”

If we treat the word through the metaphor of blood relations and identity, then of course a person has only one mother.

But from the perspective of language acquisition, a mother tongue is perhaps better understood as a linguistic system formed naturally and continuously from early childhood — one that can be accessed directly at the level of meaning.

Within a multilingual family, it is entirely possible for a child to develop more than one such system at the same time.

6 | The Real Difficulty Is Not That Children Cannot Learn — It Is That Adults Downgrade the Language First

Of course, this sounds much easier than it is.

Real multilingual family life is far more difficult than it often appears online.

Some children do not suddenly become worse at Chinese. Instead, there comes a point when their Chinese simply stops developing.

Some children switch naturally between two languages when they are young, but gradually retain only one as they grow older.

Other households may appear multilingual from the outside, yet maintaining clear and stable language roles over many years is not easy.

It was through this debate that I gradually began to see that, when multilingual education goes off course, the obstacle is often not the child.

The obstacle is the adults’ understanding of what a mother tongue can be.

Why do so many mothers instinctively believe that a person can have only one mother tongue?

What does it actually feel like to have two?

Why does a child’s Chinese sometimes not deteriorate suddenly, but simply stop growing from a certain point onward?

And why do some children switch effortlessly between two languages when they are young, only to be left with one later?

These are questions I will probably continue exploring.

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Notes

1. Xiaohongshu（小红书）: A major Chinese social media and lifestyle platform built around user-generated posts, personal recommendations, reviews, and community discussions. It is particularly popular for content about parenting, education, travel, beauty, shopping, and everyday life.

This essay is also available in other languages:

Chinese version: 母语真的只能有一个吗？

German version: Kann ein Mensch wirklich nur eine Muttersprache haben?