Geary was born in Baltimore, and grew up in Montgomery County, Maryland, where he was active in Boy Scouts, and graduated from Winston Churchill High School in 1971. While there, he earned five varsity letters in football and wrestling, and was the Maryland State runner-up in wrestling.
A graduate of Clarion University in Clarion, Pennsylvania, Geary earned a degree in Business Administration, with a double major in management and marketing. He attended college on an athletic scholarship for wrestling.
He met his wife at Clarion and married Gail Bettine in 1977. He and Gail moved to Loudoun County in 1977 and now live in Waterford in a historic home. They attend Cornerstone Chapel Church. They have three daughters who graduated from Loudoun Valley High School. They have five grandsons and one granddaughter.