Biological exogamy

In biology, exogamy more generally refers to the mating of individuals who are relatively less related genetically, that is outbreeding as opposed to inbreeding, this benefits the offspring by avoiding the chance of the offspring inheriting two copies of a defective gene and also by increasing the genetic diversity of the offspring, improving the chances that more of the offspring will have the required adaptations to survive.

Exogamy in humans
There may be a drive in humans as well as animals to engage in exogamy (outbreeding); this is because procreating with individuals who are more closely related means any children will be more likely to suffer from genetic defects caused by inbreeding. Individuals who breed with more exotic partners and thereby avoid incestuous relationships will have healthier offspring due to the benefits of outbreeding. There are many conditions that are more likely where inbreeding takes place, one example being cystic fibrosis when a couple of primarily European genetics have children, another being sickle-cell anemia when a couple of primarily African genetics have children. Therefore, the drive to reproduce with individuals genetically different from oneself may derive from an innate drive to seek the healthiest combination of DNA possible for one's offspring by outbreeding.

Conversely, exogamy can cause serious difficulties in modern medicine; for example, exogamous patients who require organ transplants may find it difficult to find matching donors.