ABC's 20/20 Presents 'My Ultra-Modern Family' Tonight, 7/13

How far will some women go to become a mom? In a surprising trend, thousands of women and couples are turning to a bold new option: instead of expensive and invasive sperm banks and fertility clinics, they're getting free sperm on the internet. "20/20" follows several women desperate to have children and willing to turn to this underground universe of online link-ups, meeting men on the internet to exchange this gift of life. But the possible rewards are not without risks.

Who are these women willing to take the chance on free, untested sperm, and who are the men willing to supply it, often donating in the most unexpected places? Elizabeth Vargas investigates the brave new world of online donation on "20/20," tonight, July 13 (9:00-10:00 p.m., ET) on the ABC Television Network. 

ABC News' acclaimed series "20/20" has distinguished itself as one of the most esteemed news programs in broadcast journalism. Amid the heated, competitive environment of primetime entertainment, "20/20" has demonstrated its ability to consistently attract a significant segment of the viewing audience by offering viewers more choices and more chances to learn about the world around them. For over three decades, "20/20" has continued to combine hard-hitting investigative reports, newsmaker interviews and compelling human interest and feature stories that have changes lives.

The program is co-anchored by the broadcast team of Elizabeth Vargas and Christopher Cuomo, both award-winning journalists.

Vargas also reports on the secret world of polygamy with a rare look inside the Darger family of Salt Lake City - a family with one husband, three wives and 24 kids.