Out of just 90 women (16.8%) currently serving in the U.S. Congress, two of them are sisters. Loretta Sanchez (D-CA), who was elected to the House in 1996, and her younger sister Linda Sanchez (D-CA), who was elected in 2002, are the first and only female duo to ever serve on Capitol Hill.
The Sanchez sisters did not inherit their political power. Conversely, they grew up working poor, daughters of Mexican immigrants who struggled to raise seven children on the father's earnings as an industrial mechanic and mother's odd jobs cleaning houses and selling Avon products. "When you come from a large family you have to scrap and fight for everything you get," Linda recalls, "but it had many advantages. You learn diplomacy, teamwork, coalition building—skills that help me in my job today."
They also pushed each other to better themselves. Loretta, who is nine years older, led by example, pursuing both undergraduate and master's degrees, entering the world of business and then eventually running for and winning a seat in Congress. She also explicitly urged Linda to aim higher. When she began applying to local California colleges, Loretta said: "You could go anywhere—Stanford, Brown, Berkeley. Let's apply to those." Linda was surprised when she got in, and she later achieved a bachelor's from UC Berkeley and a law degree from UC Los Angeles. When Linda started working as a lawyer and grappled with being one of the only women, Loretta counseled, "Toughen up. Work harder. Don't let it get you down."
Linda had some surprises for her sister too. After Loretta had been in Congress for almost six years, she called her up to say she was also interested in serving. Loretta didn't like the idea at first. "Who wants their baby sister to come play in the sandbox?" she says. But when she considered the low numbers of female political leaders—not to mention Latinas—she decided to help. Now, she says having her sister there is like having an extra pair of eyes and ears.
While the percentage of female leaders remains dismal, you don't have to look far to find that in several industries power women come in pairs. Of the 35 women (3.5%) leading America's 1000 largest companies, Denise Morrison, CEO of Campbell Soup, and Maggie Wilderotter, CEO of Frontier Communications, share the same parents. Similarly, beloved PepsiCo CEO Indra Nooyi has a sister, Chandrika Tandon, who is a Grammy-nominated artist and trustee of New York University.
In the world of sports, Venus and Serena Williams together hold 80 singles titles and 39 doubles titles in tennis. In Hollywood, Kathleen Kennedy has produced mega hits like War Horse, Jurassic Park and ET while her twin, Connie Kennedy, has helped manage films like The Adventures of Tintin and Indiana Jones. In fashion and entertainment, twins Mary-Kate and Ashley Olsen went from child stars to a design duet with clothing line Elizabeth & James, and award-winning sisters Kate and Laura Mulleavy founded clothing brand Rodarte, which has collaborated with The Gap and Target.
Last year, FORBES explored the idea of inter-generational achievement, asking if success is passed along from one generation to the next. Yet when siblings—containing near identical genetics, experiencing similar childhoods and instilled with matching value systems—ascend to power independently from their parents, one wonders if they are wired for success.
Deborah Tannen, professor of linguistics at Georgetown University and author of You Were Always Mom's Favorite, says a "success gene" in unlikely but believes home environments and a sister's success may set the stage for mutual accomplishment. "It is a combination of competition and inspiration," she says. "Maybe you have to see someone like you achieving to feel that you could do it." In research for her book on sisters, Tannen spoke to several who said they wouldn't have considered aspiring if their sister hadn't first set the example that it was possible.
Jodi Kahn, president of iVillage, an online women's network with 30 million users, says her childhood was a major contributor to her and, likely, her siblings' success. Kahn is a fraternal quadruplet, with two sisters and a brother. Growing up on Long Island, New York, the three girls shared a bedroom and stayed up late most nights talking. The social intelligence and feeling of support that she gained early on followed her to the corporate world. In executive positions at Time Inc., Reader's Digest and eventually iVillage, where she increased page views by 49% and engagement by 27%, she utilized her experience as a master collaborator and mobilizer of people.
Her siblings have also done well. Lisa Hartstein, a trained epidemiologist, directs funding at the Florida division of nonprofit Susan G. Komen for the Cure; long-time distressed debt trader John Brecker worked at Bear Sterns before co-founding a New York-based hedge fund; and Allison Shearmur worked at Columbia, Paramount and Universal studios before becoming the president of production at Lions Gate in California, where she brought highly anticipated series The Hunger Games.
"We come from a family where work is very important, but also one of understanding, support and dynamic energy," says Kahn. In her research, Tannen discovered that it is especially important for women to feel truly understood and supported as they navigate careers and leadership positions, and an equally successful sister can easily relate.
Kahn also notes that having her sister, Shearmur, at a similar level of success in the same industry opens up her network and knowledge base on both coasts, boosting business opportunities. In fact, Shearmur recently helped Kahn place iVillage branding in the backdrop of upcoming movie What to Expect When You're Expecting, starring Cameron Diaz and Elizabeth Banks. "We connect each other," Kahn says. "Between the four of us, we know so many people."
While there's mostly upside to having a powerful sister—contact sharing, support and informed advice—there can be disadvantages too. You're more likely to be compared to each other and, because you stand out, face greater scrutiny. Congresswoman Linda Sanchez says many people lump her and her sister together, assuming they agree on everything and are joined at the hip. It came as quite a surprise, she notes, when she supported Barack Obama and Loretta supported Hillary Clinton in the presidential primaries.
Working alongside one another also adds another layer of politics to their already political jobs. Loretta admits that it's hard to relinquish the role of older sister even in professional environments. "She bristles sometimes," Loretta says. "One time, Linda came into the Congress talking with her colleagues, and I walked over and asked if she'd gotten her flu shot. She hadn't, and it was the last day. So I said, 'You'd better get it right away!' She didn't like that."
"Sometimes in Loretta's eyes, I'm still 13," says Linda. "But she just had a birthday, and if I want to tease her I introduce her as my much, much older sister."