All traits were mutations at one time or another, AG. If you look at it from an evolutionary standpoint, all 'higher' organisms are the product eons of accidental mutations of non-essential genes. Normally, mutations causing advantageous traits would tend to be perserved; mutations causing disadvantageous traits would be eliminated through natural selection.
Where humans run into problems is when they select for the nonadvantageous traits--the ones that would cause the animal to be less viable in a natural setting.
Hairless cats, for example, or brachycephalic dogs.