Marni, your comment about your cholesterol resonated with me; my total is very slightly high also, for the very same reason: my HDL is so high that one practitioner told me he had never seen a number that high before. That's why the ratio is so good, too.
Emily, yes, I think you are right. There's too many of us here that were "last picked" as kids for it to be chance. Since just about everyone learns to ride a bike, it's not surprising that it is a sport people start later in life, even when we haven't had that much success in other athletic endeavors.