Forgive me for fulfilling the conlang stereotype of pedantry, but I had always believed that first language meant "the foreign language one is most proficient in" and that native languages are termed "tongues", where T1 is the language you use most regularly. Hence an Iranian-British person would have:

T1: Persian
T2: English

With L1 and L2 being whatever they learnt at school 

Sam (deliberately to spite Padraic)

p.s. words rule, numbers drool

On 5 Sep 2011, at 22:39, Gary Shannon <[log in to unmask]> wrote:

> We're all about WORDS. A reply with just NUMBERS would be contrary to
> our nature. We must find some justification for including WORDS in the
> response, hence the list of languages and other assorted constructs
> made of WORDS.
> --gary
> On Mon, Sep 5, 2011 at 1:41 PM, Padraic Brown <[log in to unmask]> wrote:
>> One thing I think is clear from this exercise -- there is no such thing
>> as a "quick" or "simple" survey among conlangers.---
>> Far more interesting to me than the pure number of languages studied is
>> the case study in survey response behavior among our group!
>> Padraic