Chinese zodiac and siblings

I'm happy that I'm a Golden Dragon, being born in 2000. However, my younger brother is a Dog born in 2006. I love him very much and would protect him from any dangers, although the Zodiac claims we're supposed to be enemies. He's like a little puppy. Anyway, here's what I was wondering in the first place: Does the Zodiac apply to siblings as well? I myself doubt it, but I want to see how other people respond, too.

P.S. Am I one of the few people who realized that G-O-D spelled backwards is "Dog"? Curious if you ask me......Something you may want to consider.