At Trivia last night my team got a question that sparked some heated discussion at our table: what percentage of old people (65+) regularly engage in sexual activity? We answered 69%, partially in homage to the topic at hand. (My guess was 70%.) Of course, our team had its share of naysayers, convinced that grannies can't get it on or that, even with viagra, the physics of the act of love just weren't possible for people with canes and walkers. This despite recent evidence of rampant STI transmission in retirement communities and assisted living facilities.
Luckily, the more optimistic among us won out. The correct answer: 68%.
Why are people so weirded out by the thought of elderly sex? I mean, why not? As long as people are aware of what's going on and consenting, the idea doesn't bother me. Although, since I brought it up, the consent issues can get pretty thorny, especially as older people grapple with demenia and families get involved. See, e.g., this heartbreaking tale from Slate.