Doug's New Jersey roots run deep. He grew up on the same Warren County farm where his parents still live. He married his wife, Trudy, in 1996, and they are the proud parents of Tia and Douglas Jr. Tia is a graduate of Moravian College and Villanova and the Vice President of Development for a national advertising and communications company. Douglas Jr. honed his skeet, trap, and sporting clay skills on the Steinhardt family farm and is a sophomore at Jacksonville University, where he earned a shooting scholarship and is a member of JU's varsity shooting team.

Doug is a graduate of Belvidere High School (1987), Gettysburg College (1991), and Widener University School of Law (1994). At Gettysburg, Doug majored in History and was a four-year starter at left guard for the football team. At Widener, he was the Associate Editor of Widener's Law Review. Doug is a proud Eagle Scout (1983). After law school, Doug returned to Warren County to practice law with his father, who retired in 2005. That same year, Doug opened a law firm around the corner from his home, where he still works today.

Doug was the first, five-term Mayor in Lopatcong Township history, serving from 2000 to 2014. Thanks to his conservative leadership, he was elected Chairman of the Warren County Republican Committee in 2004 and Chairman of the New Jersey Republican State Committee in November 2017.

Doug is a long-time, dedicated volunteer in his community. He is the founder and co-chairman of the Warren County Addiction Awareness Task Force. He also helped found and co-chairs the County Mental Health Task Force, which works to end the stigma associated with mental illness and helps connect County residents to needed services. He has served as general counsel to Law Enforcement Against Drugs (L.E.A.D.), on the campaign committee for Abilities of Northwest Jersey, the Board of Overseers of Widener Commonwealth Law School, and is a Certified, Red Cross Volunteer.