A new Census Bureau report examines the widely reported phenomena of what the bureau calls "shared households." These are defined as households that include adults who are neither the householder, the spouse, a cohabiting partner, or in school.
The bureau estimates that there were 22 million shared households in 2010, accounting for a substantial 19 percent of total households and up from 17 percent in 2007. Sixty-nine million adults (30 percent of the population aged 18 or older) live in a shared household.
To understand the shared household, take a look at the characteristics of the additional adults who live there. Eighty-two percent are relatives of the householder. Forty-six percent are a child of the householder, 13 percent are a parent of the householder, 8 percent are a brother or sister of the householder, and 14 percent are some other relative. The 56 percent majority of additional adults in shared households are aged 18 to 34.
Source: Census Bureau, Sharing a Household: Household Composition and Economic Well-Being: 2007-2010