The definition of who makes a family is shifting in the minds of Americans to include more same-sex couples, new research shows.

Brian Powell, a sociologist at Indiana University, surveyed more than 1,500 people on the definition of family in 2003 and 2006 for his new book, Counted Out: Same-Sex Relations and Americans’ Definition of Family, which was released Sept. 15.

Powell separated the people surveyed into three groups according to how they defined family: “inclusionists,” who counted same-sex couples with or without children; “moderates,” who counted same-sex couples with children but not those without; and “exclusionists,” who did not count any same-sex couples.

He found that those who considered same-sex couples with or without children as a “family” rose most dramatically from 25 percent in 2003 to 33 percent in 2010.

Powell has also conducted a 2010 survey, which is not a part of the book.

Powell found a correlation between religious ideology and how people view same-sex couples, based on whether people see the Bible as the actual word of God, the inspired word of God or a book of history and moral precepts written by men.

Those who viewed the Bible as the actual word of God were more likely to not consider same-sex couples as a family, with 65 percent falling into the “exclusionist” category.

However, Powell said the debate on whether same-sex couples should be considered as families is not a purely religious one.

People who believe homosexuality is the result of either genetics or God’s will were more open to seeing same-sex couples as a family, while those who thought parenting was the cause of homosexuality were not.

“It’s not just religious versus non-religious,” Powell said. “That’s too simple of an explanation.”