What’s it like to grow up bilingual from birth?

In this week’s post, I summarize a book chapter by Fred Genesee, a leader in the field of “simultaneous bilingualism,” or bilingualism of kids who are raised bilingual from birth (compared to “sequential bilingualism,” or kids who only start to become bilingual when they start school). Genesee shares some generally known knowledge about simultaneous bilingualism, particularly the dynamic interaction between the two languages (which are still, in his view, definitely two languages, and not an undifferentiated linguistic system) across different social contexts, different patterns of individual development (e.g., more balanced or more asymmetrical), and between cognate/non-cognate languages. There is a wealth of knowledge—decades worth—in his 15-page article… or if you want a more concise overview, in this blog post.

Genesee, F. (2022). Evidence for differentiated languages from studies of bilingual first language acquisition. In J. MacSwan (Ed.), Multilingual perspectives on translanguaging (pp. 183-200). Multilingual Matters.

When teaching this chapter in a course on language acquisition (cross-enrolled by undergraduate and graduate students), I extract four key points:

  • (1) In simultaneous bilingual kids, the languages can develop in a similar way (i.e., age-appropriate proficiency) as with monolingual kids, IF input in both languages is sufficient. For example, a French-English bilingual kid can perform like a French monolingual kid or an English monolingual kid, if the bilingual kid’s input and exposure to both languages was enough to develop both. This often requires both the family and the wider community to speak both languages generatively… and school instruction/support as well, if literacies are to be learned in addition to oral communicative proficiency.
  • (2) If input and opportunities for learning are asymmetrical, proficiency in the languages are likewise asymmetrical, resulting in the dominant language having an impact on the weaker one. That is, people are more likely to transfer sentence structures, ways of expression, etc., from their stronger language when using the weaker one. [For students learning English as a second language, I should remind teachers that this problem is addressed by strengthening authentic practice and use of the weaker language, English, rather than restricting use of the other language, which students have every right to maintain. Transfer is not only negative but can be positive—for example, if you have literacy skills in your first language, it’s easier to learn those same literacy skills in an additional language. See here for a discussion about this.]
  • (3) Even if the languages are developed asymmetrically, both are first languages; thus, simultaneous bilinguals’ code-mixing is rule-governed and systematic, suggesting nativelike intuition of the grammatical properties of two languages. I discuss that phenomenon in this post and this post. In other words, they can form a mixed language utterance without breaking the grammatical rules of either language.
  • (4) Simultaneous bilinguals adjust their language use to the interlocutor and social context, even at a very young age (including simultaneous bilingual 1- and 2-year-olds who speak in 1- and 2-word sentences). Of course, all bi/multilinguals would do so.

In what follows, I explore three topics in Genesee’s chapter: (1) bilingual language use, (2) bilingual language acquisition, and (3) psycholinguistic code-switching. Language use is how people use language, regardless of whether or not they are learning any new language or whether their language repertoire is changing. Language acquisition refers to language repertoire development. Psycholinguistic code-switching is something a person is wired to do if they are a simultaneous bilingual, which tends to be innate from that point on (so distinct from either acquisition or use).

Bilingual language use: Accommodate your interlocutor(s), whether more bi/multilingual or more monolingual

Pioneering research on simultaneous bilinguals in the 1980s showed that even very young bilingual kids have sophisticated bi/multilingual communicative strategies. For example, Genesee et al. (1996) studied four English-French bilingual kids in Canada playing with a monolingual stranger. They found that three of the kids used more of the stranger’s language with the stranger than with their parents, and three of the kids used less of the language the stranger didn’t know than they would with their parents. (This didn’t mean code-switching didn’t occur; it did when the kid didn’t know the word in the other language.) “These results suggest that the children were extending their use of the stranger’s language as much as possible and minimizing their use of the language the stranger did not know as much as possible” (Genesee, 2022, p. 186).

Comeau et al. (2003) did a more elaborate variation of the study. In their experiment, a bilingual adult played with French-English bilingual kids twice. The first time, they code-mixed sparingly (12-16% of the time). The second time, they code-mixed frequently (29-47% of the time). The third time, they went back to the low rate of code-mixing. They found that three out of four kids followed the assistant’s lead each time, even when the assistant’s language choice meant more use of the child’s weaker language. The findings suggest that, for the most part, this is what the majority of people will do: accommodate the interlocutor’s on-line language preferences, whether more monolingual or more multilingual.

To extend the findings of Genesee and colleagues, we might say that regardless of “official” classroom language policy, what happens when the teacher teaches—or when students work together in small groups—depends not so much on a policy, and not entirely on actual language proficiencies, but on how people make language choices and respond to each other’s language choices, in real time. Which begs the question of how we justify our languages choices and what impact our choices have on each other’s inclusion, on learning opportunities, and so forth.

Symmetrical versus asymmetrical language acquisition: Unlikely to be based on family or school choice alone

…but on wider social factors like the prevalence of the languages in the wider society. This key point in Genesee’s article means that parents should take what “special” language immersion schools promise with some skepticism.

Yet this is not to say that people or well-designed schools/programs have no agency. It’s more like, in one society you can have many affordances (A, B, C, D, E, F, G) and another, only limited affordances (A, B, C). In the second situation, you can STILL choose whether you’re going to settle for just A, or work towards B and C, even if it’s not feasible to get D, E, F, or G. For example, just because one is unlikely to be a fluent speaker of Russian in Australia doesn’t mean it’s impossible to teach your kids some Russian, or to ensure they can read/write in Russian and not just speak it. It’s also important for people to exercise agency, especially with endangered languages (example here).

Lit reviews by De Houwer (2009) and Paradis et al. (2011) show that bilingual kids can be fluent in both languages, as long as input in each language is sufficient. In this case, they can use each language on its own, similar to a monolingual kid, with implicit nativelike grammar knowledge and accurate pronunciation (though in my opinion, their accent will fall in between the two languages, not solidly in either one, but be close enough in both, and similar to others who are bilingual in those languages; see here for my TEDxHKU talk on this and other things). Zwanziger et al. (2005) found that kids who had mastered the grammar of both Inuktitut and English had “differentiated monolingual-like acquisition patterns” when it came to putting the subject in the sentence (a “must” in English) or omitting it (which happens in Inuktitut). Pérez-Leroux et al. (2009) found that 3-year-old French-English bilinguals in Toronto were behind French monolinguals in object pronoun use, but Paradis et al. (2006) didn’t find this result with same age French-English bilinguals in Montreal.

But when input and learning opportunities are more asymmetrical, Conboy and Thal (2006) found that grammatical complexity and productive vocabulary were correlated with Spanish-English bilinguals, within but not across languages. That is, having a lot of vocab in Spanish was predictive of grammatical complexity in Spanish, but not grammatical complexity or vocabulary in English. Yip and Matthews (2007) found that Cantonese-dominant Cantonese-English bilingual kids formed relative clauses in English using the Cantonese pattern. Döpke (1992) found that English-German bilinguals growing up in Australia (hence English-dominant) used English word order when speaking German.

Psycholinguistic code-switching: A sign of bilingual students’ competence, not their language lack

Even if proficiency is unequal across the two languages, bilingual kids have an interesting grammatical ability: the ability to reconcile the grammar rules of the languages in a code-mixed sentence. (They break the rules of neither language when they code-mix… no matter how complex the rules of each language are.) This is a nativelike competence, shown by those with two L1s. That is, it is implicit grammar knowledge. People can do it without being able to explain how it works (in the same way people have perfect grammar in L1 without being able to explain it, if they are monolingual).

Interestingly, psycholinguistic code-switching happens no matter how (un)related the languages: e.g., in studies of English + German/French/Norwegian/Chinese/Inuktitut. True, it is more flexible with related languages, like French and English, as there are fewer syntactic rules to break. But what about languages like English and Inuktitut, an agglutinating language?

Dorais (1998)

Genesee and Sauve (2000) found 4 violations out of 429 code-mixed utterances in French and English, by 2- and 3-year-olds… which meant they adhered to the rules of both languages over 99% of the time! Violations were utterances such as “my rose bat” (this violates French because French adjectives go after French nouns, and English adjectives go before nouns: “bat rose” or “pink bat”). In contrast, Allen et al. (1999) found that violations occurred at least 50% of the time among 2- and 3-year-old English-Inuktitut speakers. But were those really violations? Genesee argues that violations are actually exceedingly rare in ANY language combo because most of the violations in Allen et al.’s study were nonce borrowings such as:

Allen et al. (1999)

A nonce borrowing is simply borrowing a noun into a sentence in the other language. This practice easily transfers things/concepts across languages. If the languages are REALLY grammatically different, at least you can do nonce borrowing, as in the above example. [Side note: Nonce borrowing is quite unremarkable linguistically, unless it has some interesting sociopolitical import. I think a lot of translanguaging researchers try to pass off nonce borrowings as evidence of major language shifts in our globalized world. However, nonce borrowing is just one of the most common forms of code-switching, and has existed since time immemorial.]

Psycholinguistic code-switching is a sign of bilinguals’ language competence, not their language lack, because this kind of code-switching is evidenced by simultaneous bilinguals, whereas nonce borrowing is more widespread. On the other hand, I also discussed with my students what the limits of psycholinguistic code-switching were. Today, we discussed the question: “Sometimes it’s hard to tell whether a community is BILINGUAL, or speaks A SINGLE MIXED CODE (e.g., a creole or mixed language). How do you figure out which is the case?”

After some discussion, a number of valid answers were proposed: (1) to introduce a monolingual speaker into the community and see if people could accommodate that person by speaking just one language [if they couldn’t, they speak a mixed code]; (2) to investigate the uniformity of the code-switching [if people do it in the same way, they speak a mixed code (e.g., a creole or mixed language that has developed its own grammar and is a full-fledged language that can be acquired as a first language); if they mix languages in more individually different ways reflecting individual differences in acquisition, then it’s a bilingual community].

Of course, you could have both speaker types in the community: people who can do psycholinguistic code-switching (mixed code) as well as emergent bilinguals who tend to do nonce borrowing, for example when they don’t know the word in the other language. Of course, ability to do psycholinguistic code-switching doesn’t answer whether a person has age-appropriate proficiency in both languages, or what their literacy skills are in either language… and so a mixed code speaker still has language proficiencies in each language.

Does Genesee believe that language distinctions should be collapsed, as in translanguaging theory? He concludes:

This evidence supports the notion of underlying differentiated cognitive representations of the languages in question and, at the same time, indicates that the languages can and do interact in fluid, dynamic and linguistically constrained ways to shape both the trajectory of acquisition and patterns of interpersonal language use.

In other words, for him, different languages DO exist, but their interaction in the mind is by no means compartmentalized or isolated.


Allen, S., Genesee, F., Fish, S., & Crago, M. (1999). Code-mixing in Inuktitut-English children. Paper presented at the Eighth International Congress for the Study of Child Language, San Sebastian, Spain.

Comeau, L., Genesee, F., & Lapaquette, L. (2003). The modeling hypothesis and child bilingual code-mixing. International Journal of Bilingualism, 7(2), 113–126. https://doi.org/10.1177/13670069030070020101

Conboy, B., & Thal, D. (2006). Ties between the lexicon and grammar: Cross-sectional and longitudinal studies of bilingual toddlers. Child Development, 77(3)712–735. https://doi.org/10.1111/j.1467-8624.2006.00899.x

De Houwer, A. (2009). Bilingual first language acquisition. Multilingual Matters.

Dőpke, S. (1992). One Parent – One Language: An Interactional Approach. John Benjamins.

Dorais, L.-J. (1988). Tukilik: An Inuktitut grammar for all. Association Inuksiutiit Katimajiit.

Genesee, F., Boivin, I., & Nicoladis, E. (1996). Talking with strangers: A study of bilingual children’s communicative competence. Applied Psycholinguistics, 17(4), 427–442. https://doi.org/10.1017/S0142716400008183

Genesee, F. and Sauve, D. (2000, March 12). Grammatical constraints on child bilingual code-mixing. Paper presented at the Annual Conference of the American Association for Applied Linguistics, Vancouver, Canada.

Pérez-Leroux, A., Pirvulescu, M., & Roberge, Y. (2009). Bilingualism as a window into the language faculty: The acquisition of objects in French-speaking children in bilingual and monolingual contexts. Bilingualism: Language and Cognition, 12(1), 97–112. https://doi.org/10.1017/S136672890800391X

Yip, V., & Matthews, S. (2007). The bilingual child: Early development and language contact. Cambridge University Press.

Published by annamend

Assistant Professor in the Department of Linguistics, University of Illinois at Urbana-Champaign

%d bloggers like this: