All Tim McGraw fans know well of his baseball lineage, having MLB legend Tug McGraw as a father. Lesser-known, however, is McGraw's uncle, Tug's older brother Hank, whom Tim posted a "happy birthday" tribute to on social media Sunday (Jan. 26).

"Happy birthday to our uncle Hank," wrote Tim. "Been 'blazin'' a trail and breaking barriers since 1943!!!!"

Indeed, Hank McGraw has an interesting story that includes a fair amount of barrier-breaking along the way. Himself a baseball player who was signed to the New York Mets as one of the franchise's first "bonus babies" (a signing that sends an amateur player directly to the major leagues), Hank distinguished himself as a free spirit that didn't always fit in with the sports world. Sporting long hair and a mustache—before these were mainstream-acceptable—Hank also protested segregation in the league, and wore beaded jewelry that he would make for his teammates' girlfriends.

Following a stretch in the minor leagues and a brief stint coaching, Hank drifted into a series of various jobs, including music. He went on tour with his nephew, and helps to run the Tug McGraw Foundation in memory of his younger brother.

Tim's series of photos of his uncle reflect this free-spirited personality, showing that he still sports his long hair and drooping mustache, as well as a T-shirt with an environmentally conscious message. Scrolling through the shots, Tim includes a striking picture of Hank in his youth, clean cut for his Mets baseball card and looking an awful lot like little brother Tug.

McGraw was raised believing that his step-father, Horace Smith, was his father, and only when he was 11 did he discover that his biological father was baseball star Tug McGraw. The two established a close relationship which lasted until Tug's death in 2004.

See Inside Tim McGraw and Faith Hill's Historic Tennessee Home:

More From KLAW-FM