Inbreeding

Repeatedly choosing a small number of individuals with the desired characteristic can lead to breeding between close relatives. This is inbreeding. Relatives are genetically similar, so repeatedly breeding them can reduce the variety of alleles—the different versions of genes—in the population’s gene pool.

Selective breeding can also lead to inbreeding, where closely related individuals breed together. Relatives are more likely to share the same harmful recessive alleles. Their offspring therefore have a greater chance of inheriting two copies and developing an inherited disorder.