Researchers from Washington State University (WSU) and University of Southern Mississippi were able to establish a new classification that can differentiate gay and straight people.

The findings challenge Alfred Kinsey's Continuum Theory of Sexual Orientation, which he hypothesized in 1948. In the said theory, Kinsey said sexual orientation is part of a continuous spectrum that moves from heterosexuality to homosexuality.

Past studies on the underlying structure of sexual orientation has resulted in conflicting ideas. Some investigations found a dimensional design, such that sexual orientation may range quantitatively along a continuum. Meanwhile, other researches discovered a taxonic arrangement, which acknowledges the presence of classifications of individuals with different sexual orientations.

In the new study, the authors were able to clearly steer away from the Kinsey's hypothesis and back up more recent biological concepts of sexual orientation.

The researchers utilized information from the National Epidemiologic Survey on Alcohol and Related Conditions, which contains personal interviews of over 35,000 adults. The participants were asked about three indicators of sexual orientation, which include behavior, or the genders of people they have had sex with; sexual identity; and attraction.

Using taxometrics, a range of statistical methods that detects if people are distributed in a continuum or are part of individual categories, the authors were able to discover that three percent of men and 2.7 percent of women are not heterosexual.

The researchers also discovered significant mental health issues among the study subjects, who were not heterosexual. Roughly three out 10 non-heterosexual men exhibited diagnostic signs of depression. This finding is nearly twice as much as that of heterosexual men's.

For women, non-heterosexuals were found to be more prone to alcohol abuse and dependence.

Both non-heterosexual men and women also have greater chances to meet the standard for anxiety, other mood disorders and suicide ideation.

The researchers said social stigma may play a key role in leading gays and lesbians to develop the said mental conditions.

Ultimately, the study findings conclude that the investigation confirmed that there is a specific group of people that are heterosexuals, and there is another group, an assemblage, which is not part of the spectrum, that consists of different people binded in their homosexual orientation but may also showcase varied sexual identities.

Study author David Marcus from WSU said the results also refute the principles of the so-called "conversion therapy," which apparently moves an individuals from homosexuality to heterosexuality.

"Conversion therapy is fundamentally changing who they are," he said. "Generally we can't do that in psychology."'

The study was published online in the journal Psychological Science on Oct. 23, 2015.

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