Kin selection is the principle that genetic material could best be passed down by helping one’s relatives even if it meant the individual’s reproductive success might suffer. Bees are a prime example of this behavior. A large majority of a hive is sterile and the worker bees leave all reproductive duties to the queen.

J.B.S. Haldane, one of two men who described the evolutionary strategy in mathematical terms, wrote "I would lay down my life for two brothers or eight cousins.” This stems from the fact that, on average, siblings share 50% genetic material and cousins share 12.5% genetic material. The way the numbers work out, as long as these saved individuals passed on their genetic material, it makes sense to forfeit reproduction (read: lay down one’s life) for groups of relatives these minimum sizes.

The theory behind the genetic basis of the culture of honor has to do with the types of people who immmigrated to the different regions of the U.S. The North was populated by people of agricultural heritage and the South by people of herding heritage. Those with the agricultural heritage were used to relying on the law in order to settle disputes over land rights but, since herds are difficult to track, herding people found it important to enforce one’s own justice in the form of payback.

Sapolsky, in his book Behave: The Biology of Humans at Our Best and Worst, says that these genetic factors are just that, factors, and without the proper environmental triggers these traits would never present themselves. For example, if a newborn with a strong genetic disposition towards a culture of honor were to grow up in the Northern United States they may never display these tendencies. Throughout Behave, Sapolsky is able to provide a clear description of how there are may be many factors which affect any persons displayed behavior.