Andrei and I argued about bilingualism years before we even started dating.
He wasn't convinced true bilingualism was really possible, and I was determined to have a bilingual child in order to prove him wrong. I don't think I actually expected that we would marry each other, but I guess the thought of cross-cultural marriage didn't seem so far-fetched.
Of course, I'm oversimplifying the discussion. Here are some of the issues we argued about:
-Young children will get the two (or more) languages mixed up. I've seen clear evidence to this NOT being the case. Kids do mingle languages, but this happens when they either are missing a vocabulary word in one language, or a word is just easier to say in one of the languages. There's a more scientific way to say this, but basically it's selective, not a moment of confusion.
Although our kids insert the "other" language into their speech sometimes, they also have no problem distinguishing between the two. Case in point: Both of them, when still speaking only a few words, called us Mommy/Daddy or Mama/Papa depending on who they were talking to. Sophia will call me "Mommy" in English, but complain (ha) about "Mama" to Andrei. Same with "Papa," she will call him that to his face but turn around and tell me what "Daddy" is doing.
I guess that didn't really prove my point. Another example might be when David is talking about bugs and uses the Russian name for a bug because it's one he hasn't encountered in the U.S. or English-language nature shows. He's not confused, he just doesn't know the word.
-Bilingual kids will be behind their peers. I actually use this excuse a lot to go slower with school work. I don't completely agree because I think David in on par with his peers in many subjects. Even precocious in certain contexts. However, I will admit that if you run the numbers, it's hard for bilingual kids to receive the same input. If they are conversing 12 hours a day, in two languages equally, they will have only 6 hours of language acquisition as opposed to children who are exposed to one language. That's just the way it is. And it might not matter beyond a certain age, but there certainly might be manifestations in a younger child.
When I was preparing this year's school curriculum, I was determined to have David's Russian vocabulary coordinate with English school subjects so that he could share about what he's learning in school on a given week with anyone in either language. However, it is difficult to have it match up exactly. And even if Andrei or the grandparents work with David for a few hours per day in Russian, that isn't much compared to the 10 hours of English immersion. See next point...
-One language will be dominant. I still believe it is possible to have two native languages. My kids have heard 2 languages from birth and have been immersed in both. I really wanted to argue that someone can speak two languages fluently with no accent, and seamlessly switch back and forth. I think I still believe that to be true...however, I would have to hear some testimonies. I don't have the advantage of native speaker "intuition," having only picked up Russian in my college years.
As I mentioned above, it is pretty hard to develop areas of knowledge in two languages simultaneously, so there may be discrepancies. And so it goes that there may be greater fluency in certain topics, with preference shown to the other language when the topic changes.
It would be interesting to alternate school years in each language. Time-wise, it isn't possible to study each subject each day in both languages. And maybe that is a weird idea anyway. But as we advance in Math and History and other school subjects, I'm aware of not wanting to create a gap. I don't want my son to be stuck inside his head, able to solve arithmetic problems but not knowing the correct terminology.
So, when it comes to developing bilingual literacy, it seems that it doesn't happen so easily. It seems that it takes an intentional, consistent approach.
One more thing we argue about sometimes...
-Polyglots don't exist, they simply know several languages at a basic level. I think this is hard to test, particularly for Americans who have a reputation for only knowing one language. To be honest, I don't know if Russians are well-known for their language skills either, though I'm always impressed by those fluent in English or something else.
Again, I definitely believe people can be bilingual from birth, and I also think that it's possible to reach fluency in several other languages. I also agree with the idea that knowing multiple languages provides a certain set of skills and even triggers changes in your brain that make it easier to learn subsequent languages. Then of course, each language has that level you reach where it gets easier after you've cracked the code. So, after getting over that plateau, it could be possible to keep progressing without a huge amount of effort.
However, I'm not quite ready to buy into the advice of Internet experts who want to tell me how to learn 10+ languages. Everyone's circumstances are different. So, sure...some "experts" out there might be exaggerating, or they might be blessed with genes that make it easier to learn languages regardless of technique. But genetic or not, I do think that there are polyglots out there, and I'm a little jealous!