The new shape of multi-generational homes

Maybe it's the fault of the still-struggling economy. Or it could be blamed on the Millennial generation's slow entry into adulthood.

Whatever the cause, multi-generational households today are more likely to include adult children who have taken up residence in the spare room, rather than grandma or grandpa.

Multi-generational living is on the rise in the U.S., with 57 million people, or 18.1 percent of the country's population, sharing their homes with relatives of other generations, according to a new study from Pew Research. That's double the number that lived in multi-generational homes in 1980. The jump has been driven by young adults between the ages of 25 to 34, with nearly one in four now living in multi-generational households, according to Pew's analysis.

A multi-generational home means two or three generations living together, such as parents or in-laws and their adult children, as well as skipped generations, such as grandparents living with grandchildren. It excludes people living in group housing, such as dormitories, as well as those between 18 to 24 living with their parents, Pew said.

"The growing tendency of young adults -- male and female -- to live in multi-generational households may be another manifestation of their delayed entry into adulthood," Pew said in its report. "Young adults are marrying at later ages and staying in school longer."

Young adults may also be feeling the impact of lower wages, which could be hurting their ability to live on their own, the study noted. Unemployment is another factor for why young adults may be more likely to live with their parents, given that 25 percent of those without jobs live in a multi-generational home, compared with 16 percent of young people with jobs.

At the same time, seniors are moving away from sharing homes with younger generations. From 2010 to 2012, the share of people between 65 and 84 years old living in multi-generational homes dipped slightly, Pew notes.

"The long-term increase in multi-generational living since 1980 also reflects the country's changing racial and ethnic composition," Pew noted. "Racial and ethnic minorities generally have been more likely to live in multi-generational family arrangements, and their numbers have grown with increased immigration since the 1970s."

Asian Americans are the most likely to live in multi-generational homes, at 27 percent. Only 14 percent of non-Hispanic whites live with other generations of their families.