Should I contact a father who doesn't know I exist?

It is quite probable that my own bfather doesn't know I exist and if I ever do find out who he is (sadly my bmother has died so I can't ask her), I do plan on contacting him. Of course, you will need to be discreet. I suspect if I find out who my bfather is and call him, I would probably say that I am doing a bit of family history, ask a few questions along those lines, and then ask him if he remembers meeting my bmother. If he isn't happy about it, I would at least say that I would like some medical history. Someone I worked with had a friend who had a daughter call him out of the blue, he never knew she existed and he is thrilled so you never know until you try.