Back in middle school, everyone in my group of friends was born the same year (not that surprising, admittedly) and four out of five of us had a sibling that was two years younger. That last friend really messed things up. She was also the only one not to be born at the end of the year.
But yeah, I have a brother who's two years younger than me. I also had a sister who was nine years older, but she died a couple of years back. She was mentally handicapped, though, so I've always felt like the oldest child.