I don't have any younger siblings. My siblings are a good few years older then I am, in their mid to late 30's. I've always seemed older (probably because of a house full of older influence), and I was always told I was a pretty well-behaved kid. I've always gotten along well with the three of them, because when I was just becoming a teenager they were out of the house and leading their own lives. We are all adults now and I live a good hour away from two, and two hours from the other.
We get together for birthdays, family occasions, etc and it's pleasant enough. I only see them a few times a year. We keep in touch with occasional Facebook posts, that's all I really use it for.