Three-time New York State High School Hockey Coaches Association All-State selection as a forward, earning first-team nods in 2014 and 2015, and a second-team honor in 2013.

Did not start taking golf seriously until his sophomore season at Yale University, as he also played safety for the football team his freshman season (fall 2015).

Was on a pre-med track academically at Yale. Opted not to take the Medical College Admission Test in summer 2019 because "it expires in two years... I'm going to be playing golf longer than that."

Grandfather, Dr. James A. Nicholas, was an orthopedic surgeon and physician for the New York Jets, New York Knicks, and New York Rangers who, according The New York Times, was "a pioneer in the treatment of athletic injuries who was best known for performing four knee operations that saved the celebrated career of Jets quarterback Joe Namath." He also founded the world's first hospital-based research and clinical center for the treatment and prevention of sports injuries, the Nicholas Institute of Sports Medicine and Athletic Trauma, in 1973, and it was named for him in 1986.

James' father, Dr. Stephen Nicholas, is also an orthopedic surgeon and succeeded his father (James' grandfather) as the director of the Nicholas Institute of Sports Medicine and Athletic Trauma in 2001.

Youngest brother, Brian, was drafted by the Sioux City Musketeers the No. 8 overall pick in the 2021 United States Hockey League Draft as a high school junior. Brian also committed to the University of Michigan.

Younger sisters, Erin and Michaela, played collegiate field hockey. Erin was a decorated player at Middlebury (Vermont) College, where she made history as the first player to earn New England Small College Athletic Conference Player of the Year honors three consecutive years, was named the 2018 and 2019 National Field Hockey Coaches Association Player of the Year, and led Middlebury to four NCAA Division III national titles (2017, 2018, 2019, 2021). Michaela was a walk-on at Franklin & Marshall College, an NCAA Division III athletics program in Lancaster, Pennsylvania.

Younger brother, Stephen, played collegiate golf at Franklin & Marshall College for three seasons (2017-20), winning once as an individual.