A new survey examining America's shifting attitudes on LGBT rights pinpoints two major factors that seem to be influencing a dramatic move towards support for same-sex marriage. One of those, perhaps the most important, is a pretty huge leap in the number of Americans who say they personally have a gay or lesbian friend or family member.

Just 20 years ago, 22 percent of Americans said they had at least one person in their life who was gay. Now? 65 percent of Americans do. And according to the Public Religion Research Institute's polling, those who have family and friends who are gay or lesbian are 27 percentage points more likely to support same-sex marriage. Here's what that shift looks like: 

The data seems to lend a little weight to anecdotal evidence of the effect a close relationship to an LGBT person can have on someone's opinion. When Liz Cheney attempted to run for office on a platform that included an anti gay-marriage stance, she very publicly alienated herself from family members who have supported equal marriage rights in the past, despite being from a well-known conservative family. Why? Because her sister Mary is married to a woman. PRRI notes that the so-called "friends and family effect" presented itself in their survey "across all major demographic, religious and political groups." 

Of course, this is not to argue that these friendships and relationships have caused America's relatively rapid shift toward same-sex marriage rights over the years. For one thing, the fact that so many more Americans now have a gay or lesbian person in their lives is itself a reflection of increasing social acceptance of non-heterosexual sexual orientations. It's a safe bet to assume that a decent portion of those Americans who said they didn't know a gay person in 1993 probably did. That person, however, may not have made their sexual orientation public knowledge. 

The bottom line is this: support for same-sex marriage rights is growing rapidly, as more and more states legalize marriage equality: 17 states now allow for same-sex unions of some kind, and many of those who don't, are facing court battles to keep their laws on the books. According to PRRI, 53 percent of Americans favor marriage equality, and 41 percent oppose it. Just 10 years ago, only 32 percent of Americans supported same-sex marriage, and 59 percent were opposed.

The second factor that seems to be swinging public opinion is youth. The difference in attitudes is most dramatic when broken down by age: 69 percent of millennials support same-sex marriage. By comparison, just 37 percent of those over the age of 68 do. Take age, and factor it into virtually any other demographic measured by the poll, and you see that dramatic leap over and over again: 

  • 50 percent of millennial Republicans support same-sex marriage, compared to 18 percent of Republicans over the age of 68. Overall, 34 percent of Republicans support it. 
  • 43 percent of millennials who identify as white, evangelical protestant Christians support same-sex marriage. 19 percent of those over 68 in the same demographic do. Overall, just 27 percent of white evangelicals support equal marriage. 
  • 59 percent of black millennials support same-sex marriage. Overall, 39 percent of black Americans agree. 

The whole study, which covers a broad range of questions about American attitudes towards same-sex marriage over time, is available here