All About Bill Gates' Siblings, Sisters Kristianne and Libby Gates

Bill Gates grew up with two siblings, his sisters Kristianne and Libby, in a home that was encouraging but valued competition.

The Gates family lived in Seattle, where their late dad Bill Gates Sr. worked as an attorney while their late mom Mary Maxwell Gates was a businesswoman who served on the boards of several organizations and academic institutions during her life.

The three Gates siblings were raised on frequent game nights, playing board games, cards and ping-pong, according to a 2009 Wall Street Journal profile on the family, and followed traditions like Sunday dinners and matching pajamas during Christmas.

It helped establish a home that led to all three kids finding success in their lives and careers, which Bill attributed to their parents.

“My sisters, Kristi and Libby, and I are very lucky to have been raised by our mom and dad. They gave us constant encouragement and were always patient with us,” Bill wrote on his blog while remembering their dad after he died in 2020.

Here's everything to know about Bill Gates’ sisters — Kristianne and Libby — and their familial relationship.

They’re both married with children

Kristianne, born in 1954, and Libby, born in 1964, are private, keeping most details of their lives and their families out of the public eye. Though there isn’t much information about their relationships, Kristianne and Libby are married and use their husbands’ last names.

Kristianne, who also goes by Kristi, is married to John Blake with whom she shares two children.

Meanwhile, Libby wed Nick MacPhee, a former Microsoft executive, and she was previously married to Doug Armintrout, with whom she shares three children, according to The Seattle Times.

Kristianne is a certified public accountant

Kristianne graduated from the University of Washington in 1975 and worked at Deloitte, Haskins & Sells, where she eventually served as a partner.

She started her own firm in 1987 after she grew tired of working at a big company, which she told the Spokane-Review in 1996, had meant she had to move away from Seattle.

After discussions with her husband, who had previously lived in Spokane, Washington, the couple decided to make the move there.

“It was totally a lifestyle decision,” Kristianne told the outlet of making the move and starting her own practice, Kristianne Gates Blake, PS., in Spokane.

Libby works as a therapist in Seattle

Libby still resides in Seattle where she works as a therapist for Seattle Family Support.

According to her bio on the website, Libby leads Seattle Family Support’s The Daring Way program that follows the work of Dr. Brené Brown.

Through the program, Libby facilitates “highly experiential groups” where she focuses on “developing shame resilience skills and developing a courage practice that transforms the way we live, love, parent and lead” according to her bio.

“I approach life and my profession with an enthusiasm for growth and wholehearted living,” she wrote.

They held roles at the University of Washington like their parents

Kristianne and Libby directly followed in their parents’ footsteps by joining the Board of Regents at the University of Washington. The Gates family has a deep history with the school, where Bill Sr. and Mary met and Kristianne later also attended.

Mary was the first to serve on the Board of Regents in 1975, with her tenure lasting 18 years before her death in 1994. Bill Sr. joined in 1997 and stayed on for 15 years. Kristianne joined her dad on the board in 2006 and served until 2018, while Libby served from 2019 through 2023.

Libby stepped down in 2023, ending a streak of Gates family members on the board that started with their mom in 1975, with only a brief interruption in the ‘90s after Mary died.

They’re involved in philanthropic work

Kristianne and Libby are involved in philanthropic work, taking after their late parents in supporting causes like education and serving as board members for various organizations.

“They're definitely daughters of their mother,” said their late dad in 2004 as he outlined the causes they were involved in. “It's a list of things that you could almost just cut and paste from Mary's resumé.”

Kristianne has served on the boards of YMCA Retirement Fund, Saint George's School, YMCA of the Inland Empire, Spokane Area Chamber of Commerce, Junior League of Spokane, UW Medicine and the Higher Education Coordinating Board.

In addition, she has been on the board of United Way of Spokane County, the local chapter of the national non-profit organization her mom worked with during her life. United Way, according to the organization's website, works to improve "education, economic mobility and health."

Libby has also served on the boards of Seattle Children’s Hospital, the Make-A-Wish Foundation, the Seattle Foundation and the UW Carlson Leadership and Public Service Center. She’s been involved with the boards at Santa Clara University and Lakeside School as well.

"I'm trying to model myself after my mother's life," Libby, who was 30 when her mom died, told The Seattle Times in 1997.