Today, more than four-in-ten American adults have at least one step relative in their family – either a stepparent, a step or half sibling or a stepchild, according to a nationwide Pew Research Center survey. People with step relatives are just as likely as others to say that family is the most important element of their life.  However, they typically feel a stronger sense of obligation to their biological family members (be it a parent, a child or a sibling) than to their step relatives, the survey finds.

Several sweeping changes in the demography of American family life in the past half century – including increases in divorce and in the share of babies born out of wedlock – have contributed to the prevalence of step relatives.

Among the 2,691 adults surveyed by the Pew Research Center from October 1-21, 2010, 42% say they have at least one step relative. Three-in-ten have a step or half sibling, 18% have a living stepparent, and 13% have at least one stepchild.

Read the full report, A Portrait of Stepfamilies, on the Pew Research Center Social and Demographic Trends Project Web site.