Boris Johnson is the latest high-profile Tory to insist that those with a higher IQ will achieve most in life, and a difference in intelligence is at the heart of the equality gap.
In a highly controversial speech, attacked by political opponents, Johnson said that any discussion about equality had to take account of the fact that while 16% of "our species" had an IQ below 85 while around 2% had an IQ above 130, adding: "The harder you shake the pack, the easier it will be for some cornflakes to get to the top."
But what does the science say?
"The best way to design your baby is still to send him to Eton," the renowned genetics professor Steve Jones wrote almost decade ago, when the hype around the potential to breed your own supermodel genius was at its peak.
None disagree more, it seems, than the blonde-haired Mayor, who went to Eton.
On Wednesday night, Johnson asked the City of London audience if there were "16 per cent" of them with a low IQ.
"And for one reason or another – boardroom greed or, as I am assured, the natural and god-given talent of boardroom inhabitants - the income gap between the top cornflakes and the bottom cornflakes is getting wider than ever."
Speaking on his weekly radio phone-in on LBC 97.3, Clegg accused the mayor for talking about people as if they were a "breed of dogs" and said politicians should be seeking to improve opportunities for all.
"Much though he is a funny and engaging guy, I think these comments reveal a fairly unpleasant, careless elitism that suggests we should somehow give up on a whole swathe of our fellow citizens," he said.
"Our job in politics is surely not to simply say we are going to hive off one bunch of people and put them in one category and kind of basically say they are parked and that there is not much we can do about them. Instead what we should be doing is saying we should be instilling an opportunity culture."
The innate intelligence, or otherwise of human beings has been batted around earlier this year by Conservative politicians.
Dominic Cummings, a then special advisor to Education Secretary Michael Gove, is convinced that a child’s fate lies in its DNA, and maintains that a pupil's performance at school is part of their genetics and IQ, rather than the quality of teaching they are able to access.
Genes could be the explanation for the equality gap too, Johnson hinted last night, saying: "Some put it down to assortative mating –the process by which the massive expansion of the female population in higher education has meant an intensification of marriages and partnerships between university-educated couples, and an increase in their economic advantages.
Much of the data on whether our lives are pre-ordained by our genes is based on research by Professor Robert Plomin, a leading behavioural geneticist, which shows that familial resemblance for IQ is just due to genetics. In other words, that we inherit our intelligence from our birth parents, even if we are adopted. Plomin has discussed his ideas at length with Gove.
In a interview with the Spectator, Plomin points out those studies which show children are more likely to do well at school if they are surrounded by books, miss the point that more intelligent parents are more likely to have books in the house.
But many scientists and sociologists disagree that your genetics set your path to be a top banker in the City of London, or someone who hoovers under their desks.
In 2011, in an article for Nature, UCL's Professor Cathy Price published a study which suggested IQ is not constant, testing teenagers over the course of four years, and finding significant changes.
Some had improved by more than 20 points, others had fallen by a similar amount.
Sue Ramsden, first author of the study said when it was published: "We found a clear correlation between this change in performance and changes in the structure of their brains and so can say with some certainty that these changes in IQ are real."
The researchers said it was certainly "possible that education had a role in changing IQ, and this has implications for how schoolchildren are assessed."
"We have a tendency to assess children and determine their course of education relatively early in life, but here we have shown that their intelligence is likely to be still developing," said Professor Price.
"We have to be careful not to write off poorer performers at an early stage when in fact their IQ may improve significantly given a few more years."
And more evidence suggests that poverty can have a distinct effect on a person's ability to think and make decisions, and affect their performance in academics, no matter how smart they might be.
Being preoccupied with money problems was equivalent to a loss of 13 IQ points, losing an entire night's sleep or being a chronic alcoholic, according to the study by Anandi Mani, a research fellow at the Centre for Competitive Advantage in the Global Economy at the University of Warwick.
Sendhil Mullainathan, a professor of economics at Harvard University and a co-author of the study, stressed that the research did not show "that the poor as people have less cognitive capacity but that anyone experiencing poverty would have less capacity.
"I realise this is basic but it is such an easy mistake to make in interpreting the conclusion."