20th century
According to Terry Gould's The Lifestyle: a look at the erotic rites of swingers,[8] swinging began among American Air Force pilots and their wives during World War II. The mortality rate of pilots was high, so, as Gould reports, a close bond arose between pilots that implied that pilot husbands would care for all the wives as their own—emotionally and sexually—if the husbands were away or lost.[9] Though the origins of swinging are contested, it is assumed American swinging was practiced in some American military communities in the 1950s. By the time the Korean War ended, swinging had spread from the military to the suburbs. The media dubbed the phenomenon wife-swapping.[citation needed]
Online swinging took off in the late 1990s due to the rise of the Internet and became more prevalent towards the latter half of the decade. [edit]
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My parents were confronted with this phenomenon in the 1950s while stationed overseas. It seems that it was not unusual.
That’s interesting. Not that I’m going to try it or anything. But I bet if the people doing it had glowing arrows pointing them out people would be amazed.