Genes and Human Behavior
Animal breeders, who bred and selected for loyalty in dogs, or speed in horses, or docility in cattle, were probably the first to notice the powerful influence of heredity, even if they didn't know the word or understand the principles. Certainly all successful breeders realized that much could be known about the traits of a newborn animal by having a thorough familiarity with the bloodlines of that animal. The bloodlines of racing horses in England have been recorded in the Stud Book for more than 200 years. The impetus for keeping this record for so many years is the sure knowledge that a cross between two slow horses will virtually never produce a fast horse. This simple perception is an affirmation that, to at least some extent, DNA is destiny. The first Stud Book, published in 1793, listed almost 200 horses available for sire, but only 3 of those horses have had offspring through all of the intervening years. Thus, every thoroughbred racing horse in the world today can trace its ancestry back to one of these 3 horses. Yet, even though the bloodline of each racing horse in the world is known, in some cases back for more than 20 generations, breeding a faster racehorse remains somewhat a matter of chance. While DNA may decree destiny, the destiny it decrees is apparently not a fixed and immutable one.
The medieval preoccupation with the bloodlines of nobility, or the Victorian emphasis on noble breeding as a prerequisite for inclusion in polite society, both may originate from the perception that genes can determine the future as well as the past.