Here's why:

* Inbreeding: Involves mating individuals that are closely related, increasing the chance of homozygous genotypes (having two identical alleles for a trait). This can lead to reduced genetic diversity and an increased risk of recessive genetic disorders.

* Outbreeding: Involves mating individuals that are unrelated, leading to increased genetic diversity and a reduced risk of harmful recessive traits. This is generally considered beneficial for a population's health and adaptability.

Outbreeding can also be called crossbreeding or heterosis.