Paul Kiernan:

The American Dream of upward social mobility is less common than once thought, and it has become increasingly difficult for workers to achieve in recent decades, according to new study.

Just over half of Americans born in the 1980s have ended up with better jobs than their parents, according to an article by New York University sociology professor Michael Hout in the journal “Proceedings of the National Academy of Sciences.” That’s down from two-thirds of people born in the 1940s.

“Your circumstances at birth—specifically, what your parents do for a living—are an even bigger factor in how far you get in life than we had previously realized,” Mr. Hout said in statement.

The study approached social mobility by assigning scores to occupations ranging from housekeeper to surgeon, based on the idea that people’s jobs provide a reliable indicator of their socioeconomic standing.

In many cases, upward mobility as defined by Mr. Hout would hardly be noticed by a layperson. One point on the author’s scale corresponds to the difference between a receptionist (26 points) and a hairdresser (25 points). A 15-point improvement—from food-preparation worker to medical assistant, for example—is more perceptible but has also become considerably rarer. So-called “long-distance mobility” from one generation to the next declined from 37% of men born in 1945 to 22% born in 1985.