Genetics can play a significant roll in attraction. Close family members who are raised apart and then who meet for the first time as adults can experience significant physical attraction. Usually individuals are desensitized to genetic attraction by association with close relations during childhood. New studies are reporting that the increase in sperm donation may increase the incidence of half-siblings and half-cousins meeting as adults and experiencing genetic attraction.
Widespread semen donation may result in a significant increase in unintentional genetic attraction, accidental consanguinity, and genetic diseases in offspring of close relations. The increase in genetic disease may then be used as an excuse to require all married couples to undergo genetic screening and even artificial, non-random genetic selection and manipulation.
Fertility clinics claim the likelihood of accidental consanguinity is kept low with doctors limiting the number of times that each donor's sperm can be used. However, the media routinely reports on individuals who donate semen prolifically on Craig's List and fertility clinic doctors or employees that replace semen samples with their own.
The consequences of having so-called "designer babies" is a disruption in Hardy-Weinburg genetic equilibrium resulting in increased phenotypic variation (human breeds) but decreased genotypic variation and overall decreased genetic fitness. The consequence of non-random genetic selection is domestication and breeding our posterity into a permanent genetic slavery.