When Gallup first asked about the origins of same-sex orientation in 1977, Americans were much more likely to attribute it to upbringing or environment. Although the gap in favor of external factors shrank somewhat over the next two-plus decades, it remained the more common belief.

Throughout most of the last decade, Americans were generally divided in their views, though there were times when they tilted slightly more in the direction of environmental factors (2003-2005) or toward a birth factor (2006-2008).

The 2012 Values and Beliefs poll marked the start of a trend toward an increasing belief that people are born with a same-sex orientation.

Compared with 2011, when Americans were equally divided on the origins of same-sex orientation, most major U.S. subgroups have shown at least a slight increase in the percentage believing same-sex preference is something a person is born with. Now, a plurality of most subgroups hold that view, except for Republicans, conservatives, and weekly church attenders.