i dont think so but just cause we know its not his father could be an uncle or cousin who knows. maybe this will shed a little bit light on it but unless she insists that dr. phil is his dad then there is the anwser. go to http://en.wikipedia.org/wiki/Tim_mcgraw
Tim McGraw was born Samuel Timothy Smith in Delhi, Louisiana, a town in Richland Parish, the son of a waitress, Elizabeth D'Agostino Trimble, and a relief pitcher for the New York Mets and the Philadelphia Phillies, Frank Edwin McGraw Jr. also known as Tug McGraw. McGraw is 25% Italian and 25% Irish on his mother's side and Scots-Irish descent on his father's side.
Raised by his mother in Start, Louisiana east of Monroe, McGraw grew up believing his stepfather, Horace Smith, was his birth father. At age eleven McGraw discovered his birth certificate while searching his mother's closet to find pictures for a school project. After his discovery, his mother revealed that his biological father was Tug McGraw, and took Tim to meet him for the first time. At first, Tug denied being Tim's father. Tim was 18 years old when Tug first realized how much Tim looked like him at that age, and the two remained close until Tug's death in 2004.
As a child, Tim McGraw loved to play competitive sports, including baseball, even though he did not know Tug McGraw was his father. He studied sports medicine at Northeast Louisiana University on a baseball scholarship, and roomed with former NFL quarterback Doug Pederson where he became a member of the Pi Kappa Alpha Fraternity. While in college he sang in a band that was known as the Electones. During this period, he learned to play guitar and would frequently perform and sing for tips, although he claims that his roommates often hid the guitar because he was so bad. In 1989, on the day his hero Keith Whitley died, McGraw dropped out of college to head to Nashville and pursue a musical career