Same-sex marriage is a politically divisive issue, with support for and against often following party lines, but Americans' attitudes about it might be rooted in personal relationships.
A majority of Americans now say they have a close friend or family member who is gay, according to a new poll from CNN. This marks a sharp shift from just two decades ago, when most said they didn't have any close friends or family members who were gay.
And in CNN's poll, more than half of those surveyed said that marriages of gay and lesbian couples should be recognized as valid by law, with 42 percent opposed. Just four years ago, those numbers were flipped, with more opposing than supporting.
Academics and advocates have long said that people coming out of the closet can change the attitudes of friends and family, and this poll suggests there might be a strong link between more lesbians and gays coming out and rapidly shifting attitudes towards same-sex marriage.
Since early in the last decade -- when more than a dozen states passed constitutional amendments banning same-sex marriage and the Massachusetts Supreme Court ruled it was unconstitutional to allow only straight couples to marry -- each year more Americans have said they think gays should have the right to marry.
Among the group surveyed this year, 60 percent said they have a family member or a close friend who is gay or lesbian, an amount 15 percentage points higher than what was recorded in CNN's 2007 poll. In 1994, the percentage was even smaller -- less than one-third of those surveyed by CNN reported a close relationship with a gay or lesbian person.
"The poll confirms what we have known for some time," said Suzanne Goldberg, a professor at Columbia Law School who specializes in sexuality and gender law. "American attitudes about gay and lesbian people and about marriage equality for same sex couples have been changing consistently and quickly and the arc bends towards equality."
What accounts for this shift is not definitely known. Part of it comes down to the government, Goldberg said, and any legislation that protects gay people from discrimination or violence or provides additional rights will help shift attitudes, in part because it will make gay people less afraid to come out of the closet.
"Gay people coming out has prompted an enormous change," Goldberg said. Part of what has allowed so many gay people to be open is legislation over the last several years that makes it safer -- like the federal hate crime law signed in 2009 that protects victims of crimes motivated by homophobic bias, or anti-discrimination legislation in some states that protects people getting fired if their employer discovers they are gay.
"The law cannot change everything, but it can help create a safer environment for coming out," Goldberg said.
Read The Huffington Post's in-depth report on the first test case of the federal anti-gay hate crime legislation.
When people opposed to same-sex marriage or other gay rights have the chance to know someone in a group they once perceived as "other," the difference they once feared becomes less significant and worrisome, and homophobic attitudes can soften and change, Goldberg said. But in states without many protections for gay citizens -- the same states where citizens are most strongly opposed to same-sex marriage -- coming out by gays can be a dangerous prospect.
Next fall hotly contested same-sex marriage measures are likely to be on the ballot in Maine, Maryland, Washington State and Minnesota. So far, measures legalizing same-sex marriage have come about only by legislative action or court decisions. Every time initiatives supporting same-sex marriage have been put to a popular vote, they have not passed.
This fall, the key question will be whether Americans' shifting opinions will make a difference in these votes.