Hmmm, I don't think OCD is a directly inherited disease - Not as far as the basic Mendelian Inheritance goes. It's probably just like Heart-Disease: It is caused by a whole lot of genes that make us more susceptible to HAVING the Heart Disease (or OCD). However, if we look after ourselves we can manage to avoid seriousness of the conditions. Like, things such as eye-colour and hair-colour are directly inherited.
Whoa, I got off the main topic a bit there - Sorry
I also have an OCD friend and she had never heard of it before I mentioned it to her. You might be interested to hear that she then told me that her mother is the same as her. Also, my mother has OCD tendencies, but they do not appear to bother her too much.
You also might be interested to hear that ever since the onset of my depression my closest of friends have all had problems. So, we all appear to stick together.