Leslie Knipfing is the sister of actor and comedian Kevin James, star of The King of Queens and Paul Blart: Mall Cop. Knipfing is the family’s real surname: Kevin was born Kevin George Knipfing, and Leslie grew up with him and their brother, comedian Gary Valentine, in Stony Brook, New York.
Leslie has never worked in show business or given interviews, so this Scan Insider profile covers the confirmed facts about her family and flags the claims that remain unverified.
Key Takeaways
- Leslie is Kevin James’ only sister; their brother is comedian and actor Gary Valentine.
- The siblings grew up in Stony Brook, on Long Island, New York.
- Her parents are Janet Klein and the late Joseph Valentine Knipfing Jr.
- Her age, job and marital status are not publicly confirmed.
- Online claims that she has retinitis pigmentosa have not been confirmed by a reliable source.
Leslie Knipfing Quick Facts
| Detail | Information |
|---|---|
| Name | Leslie Knipfing |
| Known as | Sister of Kevin James and Gary Valentine |
| Hometown | Stony Brook, New York |
| Mother | Janet Klein, office worker |
| Father | Joseph Valentine Knipfing Jr., insurance agency owner (deceased) |
| Brothers | Kevin James (actor), Gary Valentine (comedian) |
| Nationality | American |
| Age / birth date | Not publicly confirmed |
| Profession | Not publicly confirmed |
Family Background
Kevin James was born on April 26, 1965, in Mineola, New York, to office worker Janet Klein and insurance agency owner Joseph Valentine Knipfing Jr. He “grew up in Stony Brook, New York, with a sister named Leslie and an older brother named Gary,” according to Kevin James’ Wikipedia biography.
Their father was of German ancestry and their mother is Jewish, and the children were raised Catholic. Joseph Knipfing has since died.
The Valentine Family Name
Their father’s middle name, Valentine, has become a family tradition. Gary adopted it as his stage name, and Kevin gave it to his only son, Kannon Valentine James, born in 2011, PEOPLE reported.
Leslie’s Brothers
Leslie’s two brothers both built careers in comedy:
| Sibling | Relation | Known for |
|---|---|---|
| Gary Valentine (Gary Joseph Knipfing) | Older brother | Played Danny Heffernan, Doug’s cousin, on The King of Queens; Kyle Gable on Kevin Can Wait |
| Kevin James (Kevin George Knipfing) | Brother | Starred as Doug Heffernan on The King of Queens (1998–2007); Emmy nominee in 2006 |
Kevin graduated from Ward Melville High School in 1983, studied at SUNY Cortland and started doing stand-up on Long Island in the late 1980s. In 2009 he produced the web series Dusty Peacock, starring Gary.
Whether Leslie is older or younger than Kevin has not been confirmed by a reliable source.
Relationship with Kevin James
Kevin keeps his family life private, and he has not discussed Leslie in detail in major interviews. His brother Gary, however, has worked alongside him on two sitcoms, The King of Queens and Kevin Can Wait.
Kevin has said family shapes his work. “I want to do movies that I’m proud of where my kids, at some point, can see and I can feel comfortable sitting there watching it with them,” he told CNN in 2012.
Kevin James’ Family Today
Leslie’s brother Kevin married model and actress Steffiana de la Cruz on June 19, 2004, after a blind date. That makes Leslie an aunt to their four children, who are covered in our Kevin James family guide:
- Sienna-Marie James, born September 30, 2005, who has appeared in Pixels and Hubie Halloween.
- Shea Joelle James, born June 14, 2007, named after Shea Stadium, the former home of the New York Mets.
- Kannon Valentine James, born April 24, 2011.
- Sistine Sabella James, born in January 2015.
In 2022, Kevin and his children performed together in a Long Island production of Oliver!, with Kevin as Fagin. For more stars’ children, browse the Scan Insider kids section.
Career and Personal Life
Leslie has no acting credits and no public career. Websites that describe her as a charity organizer, event manager or businesswoman do not cite any source, and her marital status and children are not publicly known.
Some pages also give a birth date of November 17, 1974. We could not find that date in any reliable record, so we treat it as unconfirmed.
The Retinitis Pigmentosa Claim
Many blogs say Leslie lives with retinitis pigmentosa, an inherited eye disease, and that Kevin supports research into it. We found no statement from Kevin, Leslie or a reputable outlet confirming this, so it should be treated as an unverified report.
Why So Little Is Known
Leslie appears to have chosen a private life, unlike her two brothers. She has no verified social media account and no public statements on record. That is common for celebrity siblings who work outside entertainment.
Our editorial policy is to publish only checked facts about private family members. You can read similar profiles in our celebrity relatives section, including Jacob Elordi’s sister Jalynn and Cardi B’s father, Carlos.
For more celebrity family bios, visit the Scan Insider homepage.
Frequently Asked Questions
Who is Leslie Knipfing?
Leslie is the sister of actor Kevin James and comedian Gary Valentine. She grew up with them in Stony Brook, New York, as the daughter of Janet Klein and Joseph Valentine Knipfing Jr. She lives privately, and her age, job and family life have not been publicly confirmed by any reliable source.
How is Leslie Knipfing related to Kevin James?
She is Kevin James’ biological sister. Kevin was born Kevin George Knipfing and uses James as his stage surname, so Leslie still carries the family name. She is also the sister of Gary Valentine and an aunt to Kevin’s four children with his wife, Steffiana de la Cruz.
Does Kevin James have siblings?
Yes. Kevin James has two siblings: an older brother, Gary Valentine, born Gary Joseph Knipfing, and a sister, Leslie. Gary is a comedian and actor who played Danny Heffernan on The King of Queens. Leslie has stayed out of the entertainment industry and the public eye.
Does Leslie Knipfing have retinitis pigmentosa?
Many websites claim she does, but we found no confirmation from Leslie, Kevin James or a reputable news outlet. Retinitis pigmentosa is an inherited condition that gradually affects vision. Until a reliable source confirms the diagnosis, it should be treated as an unverified report rather than an established fact.
Sources
- Wikipedia – Kevin James (early life and family)
- PEOPLE via Yahoo News – All About Kevin James’ 4 Kids (2024)
Featured image: Kevin James, Leslie Knipfing’s brother, at his Hollywood Walk of Fame ceremony in 2011. Photo by Angela George, CC BY-SA 3.0, via Wikimedia Commons.
