Social mobility is so frozen that it would take five generations for a poorer family in the UK to reach the average income, an OECD report says.
The economics think tank says income inequality has widened since the 1990s, with high earners accelerating ahead.
Those born before 1975 had much more chance of social mobility than those born afterwards, the study says.
"Too many people feel they are being left behind," the OECD's chief of staff, Gabriela Ramos, says.
The international study, A Broken Social Elevator?, says high earners are getting bigger rewards and consolidating wealth for the next generations.
It also says those at the bottom of the ladder are finding it increasingly difficult to help their families catch up - with social mobility declining.
Lost age of mobility
For those people born between 1955 and 1975, the research says, social mobility was a "reality", with people born into low-income families able to move up in terms of education and earnings.
But the OECD study suggests that those born afterwards, becoming adults in the 1990s and later, faced "stagnating" social mobility.
Researchers found a high likelihood of people being "stuck" in the income group into which they were born, with those born into poorer families likely to remain poor and those from high-income families going on to become high earners themselves.
There was also a trend for middle class families to have slipped further behind the highest paid - and for some to have got much closer to low earners.
In the UK, the study found only about a fifth of the children of low-income families went on to become high earners.
Almost three-quarters of the children of graduates in the UK went to university - compared with a fifth of children from low-income families.
And among the children of parents with manual jobs in the UK, only about a quarter would get managerial jobs.
Sir Peter Lampl of the Sutton Trust social mobility charity, said: "These depressing new findings should be a wake-up call."
He blamed the UK's poor social mobility on "rising wage inequality and the relationship between family income and educational attainment".
There were international differences in strengths and weaknesses in social mobility.
Nordic countries tended to have a more level playing field, researchers found, with children's futures less likely to be defined by where they started.
In Japan and South Korea, while education is more open and meritocratic, earnings were still likely to reflect background.
The United States had slightly higher levels of social mobility than the UK, but there remained strong links between background and future prospects - with only 8% of children from poorer families becoming high earners.
The report also raised concerns about inequality in access to health services in the US and its impact on mobility.
For the UK, the study says that "intergenerational mobility is relatively low, particularly in terms of earnings and education".
But the UK was ahead of Germany in overall social mobility.
The study found that wealthy families in Germany were particularly likely to pass on their advantages to their children.
But poorer German families were held back by persistent levels of long-term unemployment, lack of access to childcare and a school system that tended to keep poorer children in lower-achieving groups.
Countries such as Colombia, Brazil and South Africa were among the countries with the widest wealth gaps and lowest chances of social mobility.
Invest in training
The report says there are actions that could help to promote social mobility, such as:
- invest more in training for work skills
- tackle low-quality, insecure zero-hour jobs
- improve the "bargaining power" of employees
The researchers say that high property prices in the UK are a particular barrier - stopping people from entering the housing market and also discouraging families from moving home to get better jobs.
Ms Ramos of the OECD warned of too many families feeling left behind and thinking that "their children would have too few chances to get ahead".