Noise level: nature or nurture?

I like my doctor, despite the fact that he gives me bises when I arrive for an appointment. He's non-alarmist, he listens to me, trusts my maternal gut when something's not right with my kids, tries to understand where I'm coming from and is great with the kids. He's also really supportive of the way we raise our kids and their bilingualism.

That's why when he made his comment, I didn't think much of it. It was a normal check up with both kids present and they were both chattering away, back in forth between French (with him) and English (with me). I said to the doctor that I was both surprised and relieved that Max was so chatty because I'd read, heard and seen that boys speak later and not as much as girls. Not to mention the whole bilingual thing.

So Dr. R - who has a certain amount of experience in psychology - told me about the elevator theory. That if you ride an elevator up 20 floors with a French person, you won't know anything about them. But if you ride an elevator up 20 floors with an American, you'll know what they do, what their name is, where their from...I corrected him of course because you probably wouldn't know the American's name. Dr. R said that maybe the kids speak more because they are more American than French.

When we left, I thought, "hm interesting." Jerome has already brought up a similar point ie I speak more than him so the kids are loud and talkative like me and not soft spoken and taciturn like their Papa.

But that doesn't explain the quiet American kids or the loud and annoying French kids.

Yes, I am loud. Yes, my kids are loud. Yes, we are very loud together...much louder than the French part of the family. But I wonder if my doctor's comment was offensive or insightful. Because Dr. R is not like THAT.

So is it nature or is it nurture?