General Discussion

Father looks to be very overweight himself. But males with this syndrome are usually infertile, so seems unlikely that the father would have produced multiple children if he had the syndrome to pass to his kids. Regardless, even if the kid had any sort of syndrome, doesn't appear that these parents took him to doctors to get him medical attention. Also, the surviving daughter is described as severely overweight. I think they were all eating junk food in large quantities.