Right-wingers tend to be less intelligent than left-wingers, and people with low childhood intelligence tend to grow up to have racist and anti-gay views, says a new study.
Conservative politics work almost as a 'gateway' into prejudice against others, say the Canadian academics.
The paper analysed large UK studies which compared childhood intelligence with political views in adulthood across more than 15,000 people.
The authors claim that people with low intelligence gravitate towards right-wing views because they make them feel safe.
Crucially, people's educational level is not what determines whether they are racist or not - it's innate intelligence, according to the academics.
Social status also appears to play no part.
The study, published in Psychological Science, claims that right-wing ideology forms a 'pathway' for people with low reasoning ability to become prejudiced against groups such as other races and gay people.
'Cognitive abilities are critical in forming impressions of other people and in being open minded,' say the researchers.
'Individuals with lower cognitive abilities may gravitate towards more socially conservative right-wing ideologies that maintain the status quo.