Attended Monte Vista High School in Danville, California from 1992-1995 before leaving to Milan, Italy to model at age seventeen.
Studied acting at American Conservatory Theatre in San Francisco,
California.
Graduated from Venture HS 1996 in San Ramon, California, which runs an independent study program for actors/models, and holds a small group of graduates including supermodel Christy Turlington, also from Walnut Creek.
Mike Flanagan offered Greg a cameo role in The Haunting of Bly Manor after being fan of Greg's memoir The Disaster Artist.
His father is of Italian and Irish descent, and his mother, who was born in France, also has Sicilian ancestry.