Inbreeding

n. breeding of closely related individuals

v. repeatedly breed closely related individuals; generate within, produce within

Inbreeding is breeding between close relatives, whether plant or animal. If practiced repeatedly, it often leads to a reduction in genetic diversity, and the increased gene expression of recessive traits, resulting in inbreeding depression. This may result in inbred individuals exhibiting reduced health and fitness and lower levels of fertility.
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Inbreeding /in·breed·ing/ the mating of closely related individuals or of individuals having closely similar genetic constitutions. in·breed·ing n. [more]Inbreeding - Community and Resources

Noun
1. the act of mating closely related individuals
(hypernym) coupling, mating, pairing, conjugation, union, sexual union

(p. pr. & vb. n.)
of Inbreed