Each race (or variety) is characterized by a more or less distinct combination of inherited morphological, behavioral, physiological traits.

He theorized a heritable component in altruism and developed Genetic Similarity Theory which is an extension of W. His theory was that Muslims have an aggressive personality with relatively closed simple minds and were less amenable to reason. If they choose not to they must write one research paper.

Rushton's controversial work came under attack within the scientific community for the quality of the research and attacked by some even for being "racist". Rushton was a Fellow of the American British and Canadian Psychological Associations[citation needed] and onetime Fellow of the John Simon Guggenheim Memorial Foundation.