I joined the forums a few days ago, and I'm really impressed at the knowledge levels everyone has, and at the fact that everyone seems very nice. There's none of the "we know more than you do" feel that some royal sites have.
I'm pretty much interested in the British royal family because that was the family my mother and her mother were interested in when I was young. My grandmother could run through the line of succession to about 50 people, and I always thought that was impressive.
I also found the hemophilia inheritance interesting when I learned about in school, and my interest has grown from then.
I currently live in the UK, but I'm originally from Albany, NY, so I have a particular affinity for Prince Leopold, Duke of Albany.