My Daughter Asked Me About An Issue Of A 10

My daughter asked me about an issue of a 10 year old boy that she keeps occasionally. One thing, he hardly ever flushes the commode and when he does, the toilet will overflow. His bowel movements are so large ... as big or bigger around than a soda can and twice as long. He's slim and not very tall but his dad is a short man also. What could be causing this issue? I think she should tell the parents to get him to a doctor.