Marital infidelity has always been difficult to survey, since respondents often just lie, but a handful of new studies suggest that it is on the rise. In any given year, 12 percent of men and seven percent of women say they have had sex outside of marriage. It’s especially on the rise among older couples. Since 1991, the number of male cheaters over 60 has risen to 28 percent while female cheaters over 60 have tripled from five to 15 percent, while male cheaters over 60 have also risen. Some scientists speculate that medical advances like Viagra and better hip replacements have strengthened the necessary, ahem, hardware for elderly infidelity.