Rectal bleeding will someone help me understand causes? Cancer in the family

Rule out cancer. All rectal bleeding s are not cancers many benign lesions like hemorrhoids, polyps, fissures, inflammations, infections , foreign bodies will cause to bleed . In every rectal bleeding, first suspicion is cancer and must rule out cancer, with family history of cancer you must see your physician, for examination and endoscopy, finally assurance by professional .
Depends. Causes depend on the character of the rectal bleeding. Is it associated with bms, between bms, bright red, dark maroon, in the toilet bowel, on the toilet paper, mixed with the stool, associated with mucous. Is there pain. Most of the time this is not serious, but needs to be investigated. Workup depends on age, presentation, associated symptoms, etc. Bottom line, see a doctor.
Your doc can help. Lots of causes for rectal bleeding, including anal disorders like hemorrhoids or fissures, inflammatory bowel diseases like crohn's disease or ulcerative colitis, diverticular disease, fragile blood vessels, infection, polyps, cancers, other. Likely causes or not vary somewhat with age, other history, etc. See your doc, get checked out.