Brother and Sister Have Sex With Each Other; Odds of Birth Defects?

[lazybratsche]

@Chronos

So, of the 17 cases which had severe abnormalities, four were from autosomal recessives. What would the other 13 be from? Is there some other mechanism by which incest screws up kids?

To be more specific, four children had symptoms that matched known autosomal recessive syndromes (as of 1982). E.g. there was one case of phenylketonuria. Presumably, the rest of the abnormalities were also caused by unidentified recessive genetic disorders or something more complicated like inheriting multiple genetic variants that are all risk factors for some disorder.

[Ranger_Jeff]

I understand some studies have been done on Hutterite colonies. I caught that program when it was on a couple of years ago on TV. Many of them seemed to strongly resemble other members of the colony.

[TriPolar]

@wolfpup

Or to put it another way, breeding primarily or exclusively for appearance or other specific physical attributes that are valued in the breed, at the expense of health and genetic integrity. Needless to say, that kind of unbalanced priority is considered very unethical but there’s been altogether too much of it over the years. There’s nothing intrinsically wrong with purebreds, of course, but responsible buyers screen breeders just as responsible breeders screen buyers.
ETA: Talking here about dogs, not really familiar with cats and other pets.

Intensive breeding of dogs involves the elimination of offspring which don’t fit the desired attributes. Doesn’t this change the situation from humans where there isn’t an attempt to produce a standard form? With dogs only the problems that appear in the ideal animals will propogate.

[md2000]

@Ranger_Jeff

I understand some studies have been done on Hutterite colonies. I caught that program when it was on a couple of years ago on TV. Many of them seemed to strongly resemble other members of the colony.

Many years ago when I was out west, the popular street wisdom was that Hutterites would recruit healthy young males to expand the genetic pool, since they knew the dangers of inbreeding. Apparently the most common location, in these rumors, was Brandon Manitoba; close to many colonies and also close to a West German army training base. Since the Hutterites were from Germany, these recruits who resembled them were the ideal purebred breeding stock.