Hans Eysenck was a pioneer in many fields of psychological science and is widely recognised for his many outstanding achievements. One field, however, in which Eysenck contributed the important initial flagstones, although remains largely forgotten, is that of socio-political genetics. In this essay I outline Eysenck’s early work (c. 1950s) on the structure of political attitudes, detail how Eysenck used the classical twin design in order to examine whether genetic factors contributed to individual differences in social and political attitudes, as well as discuss the challenges of publishing such provocative findings amidst a 1970s scientific culture that tended to favour purely environmental explanations of human behaviour. Finally, I provide an overview of the development of the field of socio-political genetics over the last 40 years and briefly note some of the challenges that lie ahead for the field.