Brandon Hill, a lead researcher at the Kinsey Institute, reminds doctors and public health officials: "It is important for researchers and clinicians not to assume that their definition of 'sex' is shared by their participant or patient, and to use behaviorally specific criteria when conducting sex-behavior assessments, especially when assessing risk of HIV/AIDS and other sexually transmitted infection transmission." The cautionary advice is paired with the release of his latest study, published in the journal AIDS Care, wherein 180 gay men in the UK between 18 to 56 years old and 190 gay men between 18 to 74 were asked what behaviors constituted "having sex."
Among other things, the study revealed that 5% of respondents did not believe penile-anal intercourse was considered "sex." It also revealed playing with sex toys was "sex" to 77.1% of UK respondents, but only 55% of American respondents. That could explain a thing or two.