If there is no fecal incontinence, and the rectal discharge is only watery or whitish (mucopurulent) then this could be due to lax anal sphincter or due to infection of anus and rectum (proctitis—bacterial or fungal) or due to food intolerance or due to inflammation as seen in various inflammatory bowel disorders like Crohn’s, celiac, ulcerative colitis etc.
If one of his grandfather’s has Crohn’s then this should be looked into. Please consult your doctor regarding this. Take care!
The medical advice given should not be considered a substitute for medical care provided by a doctor who can examine you. The advice may not be completely correct for you as the doctor cannot examine you and does not know your complete medical history. Hence this reply to your post should only be considered as a guiding line and you must consult your doctor at the earliest for your medical problem.