Most Americans – 61 percent – reach the middle class by middle age, a study by the Washington, D.C., think tank Brookings Institution found, and childhood factors and circumstances were viewed as contributing greatly to a successful outcome.

The Brookings report studied why some children do better than others in eventually achieving middle-class status.

Editor's Note: 'It’s Curtains for the US' — Hear Unapologetic Warning from Prophetic Economist. 

The report cited “benchmarks” for each life stage to help predict the outcome:

• Family Formation: Being born into a family with a “non-poor married mother” who has at least a high-school diploma.

• Early Childhood: Achieving acceptable pre-reading and math skills and demonstrating “school-appropriate” behavior.

• Middle Childhood: Developing basic reading and math skills, as well as “social-emotional” skills.

• Adolescence: Graduating from high school with a grade point average above 2.5, without being convicted of a crime or becoming a parent.

• Transition to Adulthood: Living independently from your parents and receiving a college degree.

• Adulthood: Reach middle class with a family income at least 300 percent above the poverty level, or $66,000, for a family of four.

The report concluded, “Children born into middle-income families have a roughly equal chance of moving up or down once they become adults, but those born into rich or poor families have a high probability of remaining rich or poor as adults.”

But the Brookings report also showed that people can and do still succeed against the odds. Of those who came up short in all six benchmarks, 24 percent still made it into the middle class.

“[T]here are quite a few individuals who are economically successful despite lack of success during school,” the report said.

The Brookings study found that equality of opportunity in the United States compares unfavorably with that of Canada, the Nordic countries and other advanced countries.

A recent Pew Research Center report showed that the U.S. middle class has shrunk drastically over the past decade as Americans' net worth has plunged, wages declined and standards of living slipped away, Reuters reported.

Since 2001, median household income has fallen from $72,956 to $69,487 in 2010, the report said, and the median household net worth dropped from $129,582 to $93,150 over the same 10-year period.

Editor's Note: 'It’s Curtains for the US' — Hear Unapologetic Warning from Prophetic Economist.