Research by the University of Edinburgh and the UK Medical Research Council and published in the journal Intelligence, suggests childhood IQ is as important as social class in choosing political allegiance.
Previous studies have focused on class or education when examining adult voting habits.
For the research, the IQs of more than 6,000 subjects were recorded at the age of 10, before any secondary schooling.
People were than asked about their voting habits 24 years later, aged 34.
In this set of questions, people were asked how they voted in the 2001 general election, how they intended to vote, and in what other political activities they had taken part.
The researchers found people who reported voting in 2001 for the Green Party and Liberal Democrats had the highest average childhood intelligence scores.
Those who were cleverer were also more likely to take part in rallies and demonstrations, to sign petitions, and to be more interested in politics generally.
Average IQ scores at the age of 10 for people voting in the 2001 general election for various parties were:
:: Green 108.3
:: Liberal Democrat 108.2
:: Conservative 103.7
:: Labour 103
:: Plaid Cymru 102.5
:: Scottish National 102.2
:: UK Independence 101.1
:: British National 98.4
:: Did not vote / None 99.7