There are many routes to bilingualism, and individuals can develop their languages to varying degrees of native-level proficiency at any stage in their lives. It all depends on context and need. Humans have the fundamental need to communicate, and children, born into bi or multilingual contexts, will learn to interact with their entourage in the sounds that create meaning and constitute their world.
Simultaneous bilinguals are exposed to two languages from birth. An eleven-year-old illustrates this quite vividly: “I speak two different languages: French and English. I started to pronounce these two languages when I came out of my mum’s tummy.”
Even though initially children do not separate the two languages, their minds learn to identify and categorize all the sounds that constitute the phonetic DNA of the distinct linguistic systems. Many a young child has rendered adults speechless as he/she skillfully switches languages between interlocutors, manipulates complex grammatical structures, uses appropriate intonation and exploits the vast lexical reserves at his/her disposal. Research has shown that children who have regular and rich exposure to both languages on a daily or weekly basis, reach the same milestones in language acquisition and at approximately the same ages as monolingual children. In this case one could argue that bilingualism itself is the child’s first language.
Sequential bilingualism presupposes the addition of a second language to a more-or-less established first language. This could happen at age 3, 5, or later, as children leave home and enter a different language community. The initial confusion created by the new unfamiliar sounds is followed by a silent period as children observe their environment and work out the best strategy to belong: an English/Portuguese bilingual boy, thrown into a French primary school at the age of five, started giving away his toy cars to make friends; within the next three months he learnt to make sense of the strange sounds that surrounded him and started using French to make friends instead.
Ultimately, the difference between simultaneous and sequential language development does not affect the level of proficiency a child can achieve in both languages. Even though sequential bilinguals may need more time to work out the system of their second language, and employ different mechanisms to do so, both routes can lead to balanced bilingualism. The condition is that both languages are nurtured and sustained, through rich and diverse linguistic experiences. For this 14-year-old the attainment of bilingual nirvana is a fluid experience: “When I speak English, I have the impression to swim in this language. I don’t think before I speak, similar to when I speak French.”