Assortative mating is a method of selective mating and breeding capable of creating homozygosity for desired traits without having as great an effect on overall homozygosity as does inbreeding. It consists of mating phenotypically similar individuals that are not closely related. Geneticists who are concerned about the effects of traditional practices of purebred dog breeding and closed studbooks on the genetic health of dog breeds tend to recommend assortative mating as a less harmful breeding scheme, advising breeders to select the least related potential mates within their breed.