Again, there is no such thing as an inherently inferior or complicated or simple language. Because we speak language every day, and don’t remember learning our first language, it is difficult to reflect scientifically on how language actually works. So, people who say “x language was totally ‘easy’ for me to learn as an adult” may be less fluent than they realize, or, their first language may be closely related to x language on the language family tree, which can sometimes facilitate language acquisition in adulthood. Linguists call this the “typological distance” between languages. (Linguistic typology is the study of language similarities and relationships.) For example, German and English are much more closely related than German and Korean, and they share an alphabet, plus some word roots.
However, again, there are many exceptions to this; some Hebrew speakers can become outstanding speakers of French, even in adulthood, with the right circumstances. Some Spanish speakers may struggle to learn even rudimentary Portuguese. In addition, although some studies claim that being bilingual from childhood facilitates learning a third one as an adult, even after that critical period, and many believe that this must be true, it is actually very common for people who acquired two languages as children to still struggle enormously to learn a third in school. Conversely, some monolingual adults wind up being able to learn a second language through study and travel very well, due to talent, interest, and variability from one adult to the next.
What About People Who Acquired Two Languages as Children?
Many people all over the world spoke one language at home and then a different one at school, as young children. Because both languages were technically acquired in that critical period, we (and these speakers themselves!) expect them to be balanced bilinguals. However, this is rarely the case, because language dominance will occur quickly, especially if the speaker does not attend a bilingual school, or learns to read and write only in the community language. Also, if speakers don’t have other types of exposure, like regular travel to a country where they can become immersed in the other language, the school language can take over.
Linguists often refer to these bilinguals as “heritage speakers.” Heritage speakers may understand that home language better than they produce it, or, have “no accent” yet not know very basic vocabulary. The more fluent in the school language that these speakers’ parents are, the more likely the children are to lose their home language because children quickly figure out that their parents understand the school or community language. Then, their brains “resort” to the community language, in order to save resources and communicate more expediently. Heritage speakers come in many different levels of fluency, but all possess a rich and special familial and cultural connection to the home language. It can be helpful for these folks to understand that it is totally normal to default to a dominant language, and to realize how challenging it can be to maintain two languages throughout one’s life, when both languages aren’t necessary.