Here is another picture of a cow with the genetic defect causing double muscle
There is also a human currently alive with the defect! He is a SUPER BABY! http://www.usatoday.com/news/health/2004-06-23-baby-muscles_x.htm

There is also a human currently alive with the defect! He is a SUPER BABY! http://www.usatoday.com/news/health/2004-06-23-baby-muscles_x.htm