But his students disagree, saying parents' wealth is not 'deciding factor'

Mr Clark's findings were obtained using figures from the past 100 years

They will remain stuck in social status for life - and so will their children

citizens 'will not be granted opportunities for hard work'

Professor: The American Dream does not exist, according to Gregory Clark (pictured), an economics professor at the University of California, Davis

It has powered the hopes and dreams of U.S. citizens for generations.

But the American Dream does not actually exist, according to one economics professor.

Gregory Clark, who works at the University of California, Davis, claims the national ethos is simply an illusion and that social mobility in the country is no higher than in the rest of the world.

'America has no higher rate of social mobility than medieval England or pre-industrial Sweden,' he said. 'That’s the most difficult part of talking about social mobility - it's shattering people's dreams.'

After studying figures from the past 100 years and applying a formula to them, Mr Clark concluded that disadvantaged Americans will not be granted more opportunities if they are hard-working.

Instead, they will be stuck in their social status for the rest of their lives - and their position will, in turn, affect the statuses of their children, grandchildren and great-grandchildren, he said.

'The United States is not exceptional in its rates of social mobility,' the professor wrote in an essay published by the Council on Foreign Relations.

'It can perform no special alchemy on the disadvantaged populations of any society in order to transform their life opportunities.'

Speaking to CBS Sacramento, he added: 'The status of your children, grandchildren, great grandchildren, great-great grandchildren will be quite closely related to your average status now.'

However, not all of Mr Clark's students agree with his findings, with some pointing out that although parents' wealth has an effect on a child's life, 'it is not the ultimate deciding factor'.

In his essay, the professor also commented on the high number of people uprooting to the U.S., saying there is reason to believe they will 'have a much more difficult time' than previous immigrants.

'Recent evidence suggests that, in reality, social mobility rates are extremely low,' he wrote, adding that immigrating to the U.S. 'rarely changes one’s social status'.

Video courtesy of The RSA

'An illusion': Mr Clark claims the national ethos is simply an illusion and that social mobility here is no higher than in the rest of the world, saying: 'America has no higher rate of social mobility than medieval England'

'Widening social inequality': In an essay published by the Council on Foreign Relations, the professor cited figures (pictured) showing tdescendants of Latino immigrants are dropping out of high school at high rates

He even went so far as to say that immigrants - particularly, illegal immigrants (of whom, four out of five are Latinos) - are widening social inequality in America.

He cited 2009 figures relating to the educational attainment of 25 to 34-year-olds in the U.S., which show descendants of Latino immigrants are dropping out of high school at significantly high rates.

These rates are far more excessive than those of descendants of the domestic population and other immigrant groups, Mr Clark said.

FOrmula: After studying figures from the past 100 years and applying this formula (pictured) to them, Mr Clark concluded that disadvantaged Americans will not be granted more opportunities if they are hard-working

They show, he said, that although America strives to portray itself as a country of opportunity that can transform citizens' lives, it is actually no different in terms of social mobility than anywhere else.

Concluding his essay, Mr Clark added: 'The truth is that the American Dream was always an illusion. Blindly pursuing that dream now will only lead to a future with dire social challenges.'