The Government must do more to support low-income families and tackle the "yawning divide" between the richest and poorest in society, a report into social mobility has suggested.
Children from poorer backgrounds play less sport, visit fewer art galleries and display worse behaviour than those from higher-income families, the study found.
The Social Mobility Commission (SMC) report also found a growing divide between the richest and poorest families in terms of fathers reading to their children.
Although almost three-quarters of fathers now read to their children compared to just over a third in 1965.
However, the gap between those who read to their children from high-income families compared to low-income ones has widened from 15% in 1965 to 26% in 2006.
The SMC said the activities poorer children are missing out on are crucial to their development, and that those from low-income families were more likely to have behaviour and emotional problems.
Parents from a higher-income background also have an advantage in being able to support their children because they tend to have better social connections than their poorer counterparts, the report suggested.
Previously the commission has argued for the Government to establish an innovation fund to help improve parenting skills as well as looking beyond exam results to measure social mobility.
Alan Milburn, chairman of the SMC, called the findings "truly shocking".
The former Labour cabinet minister said: "Every parent tries to do the best for their kids and this report shows parental involvement increasing over time. But there remains a yawning divide in children's life chances.
"This report makes clear that parenting can no longer be a no-go area for public policy. There has been a lot of focus on improving social mobility by tackling disadvantage in schools, universities and workplaces - but social mobility begins in the home. Parenting has not received the attention it deserves. Parents provide the foundations for children's progress in later life and government must do more to support them in doing so."
Author of the report Dr Lindsay Richards, from Nuffield College, Oxford University, said: "Our research demonstrates that - well before exams are taken or application forms filled in - more advantaged children have had more investment in terms of time, they have done more extra-curricular activities, and experienced fewer behavioural problems. It is unlikely that education alone can fix the problem of unequal life chances in Britain."