I have two brothers who live in Japan.

[keannu]

It might be folly to determine only the number of brothers here, but I'd like know native speakers' perception about it depending on a comma. 1 definitely says "I have only two brothers", then what about 2?
"I may or may not have more than two brothers" or "definitely more than two brothers"?

1. I have two brothers, who live in Japan.
2. I have two brothers who live in Japan.

[Chicken Sandwich]

See this thread.

[keannu]

That thread was a little bit confusing as different posters gave different opinons. I think different teachers have different views on this stuff. Any more opinion?

[Barb_D]

I would assume that you have more than two brothers without the comma. However, if someone said "Are you 100% sure" I would not be.

[emsr2d2]

For me, #1 means you have only two brothers. #2 is ambiguous although I would probably assume that you had more than two brothers, and the other brothers don't live in Japan. However, if I went on to discover that you only had two brothers, I would not be completely surprised.

[keannu]

Thanks a lot for your endeavor.

For #2, the Korean language positions the describing clause in front of the noun "two brothers", and even if we think of it Korean, we'll have the same ambiguity. I came to affirm the fact that many languages have things in common as all human beings share the same consciousness.