Genetic determinism, the belief that human behavior is determined by an individual’s genes, accompanied with the then-new science of Mendelian genetics gave rise to eugenic theory in the beginning of the 19th century. Human behavior genetics became the primary focus of eugenic ideology, with eugenicists promoting the belief that certain social traits such as intelligence, race, insanity, criminality, homosexuality, etc. are inherited. Eugenicists around the world believed that gene therapy, sterilization, and euthanasia were the solutions to limit these unfavorable traits from existence, and governing bodies agreed.
In reality, there was little scientific evidence to prove these claims, but most members of the scientific community did not speak up publicly about the tenuous and often-exaggerated claims of eugenicists. Many thought it was largely a political movement and that it did not behoove professional geneticists to get involved in political debates, however, what resulted was the general public receiving the impression that eugenics was an accepted belief due to limited challenge of it (Allen).