Gavin Christopher Newsom is a well-known American politician, businessman, and the current governor of California
However, behind the public figure stands a close-knit family shaped by deep roots in San Francisco, early financial challenges, unwavering resilience, and a shared commitment to service.
This article focuses on the siblings at the heart of his life—his sister, Hilary Newsom Callan, and any potential brother—and delves into the family’s ethnic background.
Through personal stories, leadership roles, and philanthropic efforts, we explore the influence of family dynamics on Gavin Newsom’s character and career.
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Table of Contents
Gavin Newsom’s Family Overview
Birth & Parents
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Gavin Christopher Newsom was born on October 10, 1967, in San Francisco, California. 1
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His parents were Tessa Thomas (née Menzies) and William Alfred Newsom III, a judge and attorney connected to the Getty family.
This you? https://t.co/N6vNpdfOmO pic.twitter.com/4Eopt6pYyD
— Gavin Newsom (@GavinNewsom) August 20, 2025
Family Background & Upbringing
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Gavin is a fourth-generation San Franciscan, with deep local roots.
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His maternal great-grandfather, Thomas Addis, was a pioneering Scottish-born nephrologist.
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His father’s side traces ancestry back to Ireland.
Gavin’s childhood was marked by financial hardships following his parents’ divorce in 1971, when Gavin was just three.
Their mother, Tessa, worked tirelessly—juggling roles as a waitress, bookkeeper, secretary, and paralegal—to support her two children.2
Meet Gavin’s Sister Hilary Newsom Callan
Gavin’s only known sibling is his younger sister, Hilary Newsom Callan, born in 1968, a year after Gavin.
Despite early financial pressures, Hilary pursued a path of leadership. She joined Gavin’s business ventures early, becoming the marketing director in 1999.
By 2006, she rose to become President of the PlumpJack Group, a thriving enterprise that includes wineries, hotels, cafes, and retail ventures. Gavin fondly called her “the brains” behind the operation. 3
Philanthropic efforts:
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In 2000, Hilary and her husband, Geoff Callan, launched the PlumpJack/LINK Golf Classic in honor of their mother, Tessa Newsom, who died of breast cancer in May 2002. LINK stands for Learning, Information, Networking, and Knowledge.
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Over the years, this tournament has raised millions for cancer research. By 2009, it had raised $1.8 million, and since then, over $6 million. 4
Hilary is also a trustee of the Northern California Cancer Center and dedicates roughly a quarter of her time to philanthropic causes.
Any Brothers?
There is no credible evidence of Gavin Newsom having a brother. Public records, biographies, and reputable sources consistently mention only his sister, Hilary. That suggests Hilary is his sole sibling.
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Family Ethnicity & Heritage Overview
| Family Member | Ethnic / Cultural Roots |
|---|---|
| Maternal ancestry | Scottish (Thomas Addis, renowned nephrologist) |
| Paternal ancestry | Irish (ancestral immigration from mid-1800s) |
| Siblings | Gavin and Hilary – born in California, San Francisco roots, multi-generational city heritage |
| Family resilience | Raised by single mother post-divorce, navigating financial strain, fostering work ethic and commitment to service |
Why This Matters
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Character shaping: Growing up with limited financial resources and a hard-working single mother instilled resilience, leadership traits, and empathy in both Gavin and Hilary.5
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Business and service synergy: The siblings’ shared values led to success in business combined with impactful philanthropy.6
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Cultural grounding: Their Scottish and Irish roots, and being part of a longstanding San Francisco family, loosely inform their perspectives—even if not a daily reference.
FAQ’s
Q1: Does Gavin Newsom have any brothers?
A: No. All credible sources mention only his sister, Hilary. There’s no evidence of a brother.
Q2: What role does Hilary Newsom Callan play in Gavin Newsom’s life?
A: She’s his younger sister and the President of the PlumpJack Group, which includes hospitality and wine businesses. She’s instrumental in its growth and philanthropic outreach.7
Q3: Why is she referred to as “the brains”?
A: That nickname stems from Gavin’s appreciation of her leadership and strategic vision in running PlumpJack.
Q4: What is the LINK Golf Classic, and why was it founded?
A: The PlumpJack/LINK Golf Classic was created by Hilary and Geoff Callan in 2000 to honor Tessa Newsom and raise funds for cancer research. The acronym LINK stands for Learning, Information, Networking, and Knowledge. It has since raised millions.8
Q5: What is the Newsom family ethnic background?
A: They are rooted in San Francisco, with maternal ancestry tracing to Scotland (through Thomas Addis) and paternal roots in Ireland.9
Q6: How did family circumstances shape Gavin’s and Hilary’s values?
A: After their parents divorced, Tessa raised them by juggling multiple jobs. That upbringing fostered strong work ethics, empathy, and a drive to succeed in both business and public life.10
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Conclusion
Gavin Newsom’s family story is one of grit, unity, and a shared belief in service. His sister, Hilary, stands out as his partner in business, philanthropy, and purpose.
Together, they build a legacy rooted in modest beginnings, family loyalty, and community impact.
From their Scottish-Irish heritage to their San Francisco upbringing, the Newsom siblings reflect how heritage and hardship can shape leaders with empathy, vision, and commitment.
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