25 y/o. recurrent anal bleeding. blood in toilet, paper, can't tell if on feces or from dripping. maternal grandfather had colon cancer. anysuggestion?

Anal Fissure: This is not cancer and is very unlikely given your age. It sounds like the common condition of anal fissure. I would get in to the family clinic to be examined soon.

You need a medical c: A medical check up is required to find the cause of your rectal bleeding. It could be hemorrhoids but occasionally it can be something more serious . So you need to go see a doctor soon and find out the cause. Then they can offer you treatment to cure the problem.

See GI doctor: Make appointment with a GI doctor. He will examine you to make sure you don't have anal disease (e.g. Hemorrhoids, anal fissure) that may cause bleeding and also determine when you need your first colonoscopy (depending on what he finds on physical exam and the age at which your grandfather developed colon cancer).