Cheaters may get more attention, but couples of all types are more monogamous than they used to be, finds research on more than 6,800 people in heterosexual, gay and lesbian relationships.
"Our findings reveal a marked movement toward monogamy over time," says the study in the September issue of the journal Family Process, online now.
The study of 6,864 men and women - responses were collected from 6,082 individuals in 1975 and from 782 in 2000 - examines differences on a variety of issues, including monogamy.
"There's dramatically less extra-relational sexual behavior in the year 2000 than in the year 1975 for all couple types," says researcher Robert-Jay Green, a psychology professor at Alliant International University in San Francisco.
Although the most recent data are from 2000, Green says it allowed for a direct comparison because the questions posed were the same used in 1975.
The percentage of heterosexual men who reported having sex with someone other than their wife dropped to 10% in 2000 from 28% in 1975; among married women, it declined to 14% from 23%. Among gay men, the percentage who cheated on a partner they lived with dropped to 59% from 83%; for lesbians it declined to 8% from 28%. Half the gays and lesbians in the study were in civil unions, half were living together in committed relationships, the researchers say.
The authors "speculate that awareness of HIV/AIDS and other STDs has led couples to be more cautious and more conservative about sex outside their relationships over the last 25 years."
But Green says it's also a result of greater acceptance of same-sex relationships.
Emily Hecht-McGowan of the non-profit Family Equality Council, which works toward equality for lesbian, gay, bisexual and transgender families, agrees. "As public opinion has shifted about gay people and the LGBT community overall, I think same-sex couples are more comfortable living openly in their communities and building families," she says.
"Some might expect monogamy is not something that typifies same-sex couples, but clearly the trend is in the opposite direction," says psychologist Glenn Roisman of the University of Illinois-Urbana-Champaign. He hasn't seen the research but has studied committed relationships.
Roisman says his research about relationship satisfaction, relationship and commitment among same-sex and opposite-sex couples published in 2008 and 2009 found that past perceptions about same-sex couples are "not always aligned with the reality."
"What we found surprised some - that they had relationships of about the same quality" as heterosexual couples, he says.
By Sharon Jayson, USA TODAY