Blood in your stool can be from many things, not just colon cancer. However, blood in stool should be checked out by your doctor and treated. Its not something you want to have going on a regular basis. Talk with your doctor about getting an acurate diagnosis. Could be anything from hemmorhoids to IBD's.
Further to B_Shel20's comments above, I endorse the suggestion to get this checked out because rectal bleeding is never normal. For possible causes google rectal bleeding and click on to one of the many sites listed - the Medicinenet site is particularly informative.
You will then be better informed when you meet your doctor/specialist.
Unless your doctor can absolutely positively confirm that the cause is one of the minor ones (e..g. anal fissure, haemorrhoids etc) I suggest that you request a colonoscopy.
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