20/20 polygamy family slideshow The Dargers might strike you as average adults and children. But Joe Darger is a polygamist with three wives -- Alina and identical twins, Vicki and Valerie. Together, they are raising 24 children. <a href="http://abc.go.com/watch/2020/SH559026/VD55224469/2020-83-i-married-twins-and-donor-sexuals"><b>CLICK HERE to watch the full story on "20/20: My Ultra Modern Family."</b></a> Donna Svennevik/ABC News

20/20 polygamy family slideshow The Dargers have gone public with their unconventional family in "Love Times Three." Stepping out of the shadows is risky for the fundamentalist Mormon family because in Utah, where they live, polygamy is a felony punishable by up to five years in prison. They say they wrote the book to correct misconceptions and make a case for legalizing polygamy. The book's paperback edition is on sale Aug. 28. Courtesy Harper Collins

20/20 polygamy family slideshow Valerie, Alina and Vicki Darger admit that their plural marriage can lead to jealousy but say that, through trust and hard work, they get through it. "Always, it comes back around to trusting that we all want for each other what we want for ourselves," Valerie Darger said. Donna Svennevik/ABC News

20/20 polygamy family slideshow Alina and Vicki Darger both grew up in polygamist families. In 1989, at the suggestion of Joe Darger's mother, the women made a decision unusual even within polygamist circles and began dating Joe Darger at the same time. Courtesy Darger family

20/20 polygamy family slideshow Not everyone was supportive of Joe Darger dating the future Alina and Vicki Darger at the same time. When he approached Alina's father to ask permission to date his daughter, Joe was rebuffed. Her dad told him, "You're taking on too much, too soon." Courtesy Darger family

20/20 polygamy family slideshow After two years of dating, Joe Darger got down on one knee, took both Alina and Vicki Darger's hands and asked the women to marry him. In 1990, Joe, Alina and Vicki Darger were married in a traditional LDS ceremony. Weeks later at a civil service, Alina Darger, who is one year older than Vicki Darger, became Joe Darger's legal wife while Vicki Darger acted as a witness. Courtesy Darger family

20/20 polygamy family slideshow Ten years into Joe Darger's marriage with Alina and Vicki Darger, another wife joined the family. Valerie Darger is Vicki's twin sister. After the breakdown of her first marriage, a supportive relationship with Joe Darger turned romantic. It was Alina and Vicki Darger who noticed the connection and approached Joe Darger with the idea of welcoming Valerie into their family. Courtesy Darger family