What if the percentage of people is each segment of the “relationship lifestyle” hasn’t really changed over time. Rather, the willingness to engage and be open and get reported has changed. There’s always been lifelong bachelors or spinsters or whatever, and the way sexuality was discussed or referenced has certainly changed.

Maybe as another writer speculated that sexuality is a drive that can be applied in various directions and the choice or non choice can be influenced. But ya need fur genes to get fur.