Terisa and Matt and Vera and Larry ... believe in ethical nonmonogamy," or engaging in loving, intimate relationships with more than one person – based upon the knowledge and consent of everyone involved. They are polyamorous, to use the term of art applied to multiple-partner families like theirs, and they wouldn't want to live any other way. Researchers are just beginning to study the phenomenon, but the few who do, estimate that openly polyamorous families in the United States number more than half a million. Over the past year, books like Open, by journalist Jenny Block; Opening Up, by sex columnist Tristan Taormino ... have helped publicize the concept. Today there are poly blogs and podcasts, local get-togethers, and an online polyamory magazine called Loving More with 15,000 regular readers. Celebrities like actress Tilda Swinton and Carla Bruni, the first lady of France, have voiced support. Polys say they aren't so much denying their biological instincts as insisting they can work around them – through open communication, patience, and honesty. Polys call this process "compersion," or learning to find personal fulfillment in the emotional and sexual satisfaction of your partner, even if you're not the one doing the satisfying. "It's about making sure that everybody's needs are met, including your own," says Terisa. "And that's not always easy, but it's part of the fun." It's a new paradigm, certainly – and it does break some rules. "Polyamory scares people. It shakes up their world view," says Allena Gabosch, the director of the Seattle-based Center for Sex Positive Culture.

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