I consider myself to be fully bilingual. My mother tongue is Afrikaans and I went to Afrikaans schools, but I learned English as a toddler and was a fluent speaker by the time I went to school. I read my first (abridged) Dickens at age 10. My degree was presented only in English. My husband and I speak mostly English to each other, although I speak Afrikaans to my children. When I speak, read or write English I think in English. I more often have to translate words from English to Afrikaans than the other way around. Can I claim English to be my first language?
Yes, if you want to.
ILR Level 5 – Native or bilingual proficiency
Native or bilingual proficiency is rated 5 on the scale. A person at this level is as fluent as an educated native speaker.
Level C2: Proficient User: Mastery or proficiency
- Can understand with ease virtually everything heard or read.
- Can summarize information from different spoken and written sources, reconstructing arguments and accounts in a coherent presentation.
- Can express him/herself spontaneously, very fluently and precisely, differentiating finer shades of meaning even in the most complex situations.
Other employers or organisations may apply different criteria, of course. Some of the correspondences between CEFR levels and other English language proficiency scales are listed here. But in general it makes no difference whether you're bilingual, a native speaker, or you're speaking English as your nth language. The point is your level of ability, rather than the circumstances in which you acquired it.
I'd suggest you simply continue to describe yourself as 'bilingual' though, because it sounds as though you're essentially a native speaker of both English and Afrikaans, so that's the most accurate description.
Is there a specific reason that you need to declare it as your 'first' language as opposed to simply listing the language as 'native' or 'fluent'? What is the application of this declaration? Are you applying for jobs, or does this come up in conversation? If there is some reason that you need to distinguish one language as your 'first', then by all means, claim it. Otherwise, what's the utility of making such a distinction?
All in all, I suppose your 'first' language is the language to which you arrive initially when prompted. As far as I can tell, this does not need to be your mother tongue; indeed, I know a handful of individuals who speak English more than their mother tongue. I would consider it valid if they claimed English as their 'first' language, even if they speak it with some accent.