Why do Japanese state their reason for everything as "Because I am Japanese"?

Question:

I know not all do this, but it seems like a strange phenomenon...something as simple as, "What's your favorite color?" can be answered, "Blue, but that's because I'm Japanese." Do you like this movie, "Well, you know I am Japanese."

But it will apply to things which honestly have nothing to do with Japanese lol

Why is this? Thanks!

Answer:

I dunno. I was extremely nervous because of what happened the other day.
People blamed me for not making sense. The same people asked me "why?" again. The best reasoning I could come up with was "because I am Japanese!"