What Is Pure Breeding in Genetics?

In genetics, pure breeding involves creating offspring by mating two parents that are genetically similar. Also called true breeding, it is the opposite of a hybrid.

During pure breeding, a certain phenotypic trait passes down to offspring from the parent organism. A phenotypic trait is what people can see, such as hair color and eye color. In terms of Mendelian genetics, this type of breeding requires that the organism is homozygous, which means a single trait stems from having identical alleles. The exceptions include two types of asexual reproduction, including parthenogenesis and apomixis, because their reproduction can also result in pure breeding.