This article explores the history of inbreeding in Japan, its effects on the Japanese population, cultural attitudes towards it, current practices of it, and more. Inbreeding has been practiced for centuries to preserve family lineages and maintain certain traits within the family. The effects of inbreeding have generally been positive overall, but there are some potential risks associated with it such as an increased risk for genetic disorders due to recessive genes being passed down through multiple generations if both parents share them. Cultural attitudes towards inbreeding vary among different regions and social classes in Japan but it is generally accepted as long as all parties involved understand all potential risks beforehand. Most cases of inbreeding today involve close relatives such as siblings or cousins rather than distant relatives like royalty or aristocracy would have done historically.