When mutant, muscle-bound puppies started showing up in litters of champion racing whippets, the breeders of the normally sleek dogs invited scientists to take DNA samples at race meets here and across the country. They hoped to find a genetic cause for the condition and a way to purge it from the breed. —”As Breeders Test DNA, Dogs Become Guinea Pigs“
Wendy, the brown whippet in this photo, has a mutation in a gene that controls myostatin, which is responsible for setting some limits on how muscle grows. It’s not as simple as “let’s purge it” — many genetic disorders represent the occasional “too much” (or “nowhere near enough”) of a trait that, in moderation, is protective or functional, or simply benign (as in Wendy’s case). Wendy got this mutation from both parents, but a whippet that gets it from only one parent is substantially faster than a whippet that doesn’t carry the mutation at all.
This or similar mutations appear in people, cattle, and sheep as well, but as far as I know, no bodybuilders with this condition have taken the stage. In dogs, the genetic testing that is now contributing to selective breeding has brought up a number of ethical and practical questions about the wisdom of tinkering with genes at this level. “I always use dogs as the example of why we don’t want to be mucking around with our own genome,” Mark Derr told the New York Times in the story linked above. “These people are trying to use DNA tests to solve problems of their own making.”
This isn’t directly related to getting started with exercise, but it does illustrate one of the things it really means to say something is “genetic.” Also, I have an abiding fondness for Wendy. She may not be the fastest whippet (and she certainly doesn’t have a “thigh gap”), but she is a healthy beautiful dog.