James Thomas Fallon was born in the Bay Ridge neighborhood of Brooklyn, New York on September 19, 1974, the son of Gloria (nee Feeley) and James W. Fallon. He is of German, Irish, and Norwegian descent. His paternal grandmother, Luise Schalla, was a German immigrant from Osterholz-Scharmbeck, while one of his maternal great-grandfathers, Hans Hovelsen, was a Norwegian immigrant from Fredrikstad. Another set of great-great-grandparents were Thomas Fallon, an Irishman from County Galway, and Louisa Stickever, the daughter of an Irishman born in France and his Irish wife.

Fallon married film producer Nancy Juvonen, co-owner of production company Flower Films, on December 22, 2007. After meeting on the set of Fever Pitch, the two began dating in May 2007. Fallon proposed in August 2007 with a Neil Lane-designed engagement ring, at sunset on the dock of Juvonen's family home in Wolfeboro, New Hampshire. They were married four months later. They have two daughters. They have a female English cream Golden Retriever named Gary Frick that has appeared on Late Night with Jimmy Fallon.  On June 26, 2015, Fallon suffered a ring avulsion, an injury he suffered by tripping over a rug in his home and catching his wedding ring on a counter top which nearly tore off his finger. He was taken to the emergency room and then sent to a surgeon who performed microsurgery on his finger. Fallon spent 10 days in the ICU before going home. He discussed this on the July 13 episode of the Tonight Show and thanked the doctors and nurses who helped him. As of July 14, 2015, he was expecting to spend another eight weeks without any feeling in his finger. In an interview with Billboard magazine in September 2015, Fallon explained that his finger still had limited mobility and that another surgery would be required. He reiterated this point at the 67th Emmy Awards on September 20, 2015, where he appeared in public without his finger bandaged for the first time.  On November 4, 2017, Fallon's mother, Gloria Fallon, died from undisclosed causes at age 68 at NYU Langone Medical Center in Manhattan, New York. Scheduled taping of the following week's Tonight Show episodes were canceled. One week later, Fallon paid tribute to his mother following that night's monologue, becoming emotional and calling her "the best audience". Answer this question using a quote from the following article:

Does he have siblings?