Editor's note: This story originally ran on Feb. 17, 2015.

Justin Thomas is a 21-year-old PGA TOUR rookie, but many mementos from his young career are already on public display.

The pro shop at Harmony Landing Country Club in Goshen, Kentucky, doubles as a makeshift museum for the latest in a line of men who’ve made this game their vocation.

The front counter’s display case used to house golf balls and gloves. Now it’s filled with items Thomas has accumulated, like the Haskins Award he earned as college golf’s top player in 2012 or a caddie bib from the 2009 Wyndham Championship, where he made his first PGA TOUR cut at age 16.

There are also more than 10 dozen golf balls -- each one has a tournament name and date written on it -- in display racks in the head pro's office. There's a ball from each one of Thomas' tournament victories. The collection began while he was in elementary school. Its most recent addition came last September, when he won the Web.com Tour’s Nationwide Children’s Hospital Championship.

Thomas has come close to adding another ball. Earlier this year, he played in a final group on the weekend of three consecutive events – Sony Open in Hawaii; Humana Challenge in partnership with the Clinton Foundation; Waste Management Phoenix Open – and has three top-10s in nine TOUR starts. He’s No. 34 in the FedExCup and 84th in the Official World Golf Ranking.

"I don’t necessarily feel like a rookie,” he said. “I feel comfortable.”

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Not only has he been a promising prospect for years, but he grew up around the game. Home videos show Justin hitting a ball and chasing after it with the family dog, Fairway, while his parents, Mike and Jani, drove a cart.

Justin remembers being in the Valhalla clubhouse at the 2000 PGA Championship during Tiger Woods’ duel with Bob May; Mike had access as a past president of the Kentucky PGA.

Justin, then 7 years old, got Jack Nicklaus’ autograph that week. When he told classmates that he got the signature of golf’s greatest player, they assumed he meant Woods, who’d just won his third consecutive major at Valhalla. Justin may have been in elementary school, but he knew enough golf history to know Nicklaus was golf’s all-time major winner.

“Just a typical golf nut, from a golf family, would say that,” he said.

Mike was on the PGA of America’s national board from 2008 to 2010. The position allowed him to be a starter at the PGA Championship and scorer at the Ryder Cup. Mike represented the PGA at the 2010 Ryder Cup in Wales while Justin competed for the U.S. at the Junior Ryder Cup.

Mike’s father Paul was the head professional at Zanesville (Ohio) Country Club for more than a quarter-century, at a time when competing was a large part of the pro’s job description. He played in the U.S. Open and once was paired with Arnold Palmer in a Champions Tour event.

Three generations’ worth of United States Golf Association medals, which are awarded for winning qualifying tournaments for the organization’s national championships, also are on display at Harmony Landing. Justin was runner-up in the 2010 U.S. Junior, semifinalist in the 2012 U.S. Amateur and played last year’s U.S. Open. Mike played in the U.S. Junior, while Paul played in both the U.S. Open and U.S. Senior Open.

Harmony Landing’s short 16th hole also is testament to the Thomas’ golf legacy. Paul, Mike and Justin have all aced the hole. Justin was approximately 6 years old when he holed out with a driver from 136 yards.

The Thomas patriarchs’ accrued wisdom, and a private course that openly embraced its head pro’s son, helped turn Justin’s early potential into a PGA TOUR card.

Mike has been the head pro at Harmony Landing since 1990. Justin was born three years later and quickly became a fixture at his father’s office.

“The members have supported him since Day 1,” Mike said. They “pushed me out the door,” Mike said, to caddie for Justin at the 2009 Wyndham. Mike had planned to stay at Harmony Landing because the course’s member-member was the same week.

“Every member and guest who comes into Harmony Landing wants to hear Justin stories.”

Justin’s early success has induced comparisons to Jordan Spieth, with whom Thomas has competed since junior golf. Both made PGA TOUR cuts while in high school and represented the U.S. in the Walker Cup, amateur golf’s version of the Ryder Cup.

Justin was college golf’s player of the year in 2012. He beat out fellow freshman Spieth for the honor; they were 1-2 in Golfweek’s individual rankings. Thomas won a school-record six times in two seasons at Alabama, and led the team to the 2013 NCAA title.

Jay Seawell, the head coach at Alabama, said Thomas’ biggest strength is his ability to be comfortable in uncomfortable situations. Take the 2013 Web.com Tour Q-School, where he rebounded from a third-round 78 to shoot 69-66-65 over the final three rounds and earn full status. He had just three scores higher than 72 in 20 Web.com Tour starts last year, needing just one season on that circuit to graduate to the PGA TOUR.

“Mike gave him a … love of playing. He didn’t make him a lover of golf swings,” Seawell said. “Mike did a great job of making Justin love Nos. 1-18. He was always on the golf course, playing with his dad. I think the more you play, the more you value the score.”

Father and son competed early and often, and weren’t afraid to exchange friendly banter. Mike was an all-conference player at Morehead (Kentucky) State. He relied on a strong short game that was good enough to challenge his son for many years.

At 2 years old, Justin would say, “Bag of balls,” when he wanted to head to the driving range, Mike said. Justin was there all day during the summer, allowed free reign of the facilities. An assistant pro or Jani would often watch the pro shop in the late afternoon so Mike could play some holes with his son.

When Mike encouraged his son to take days off after weeks competing on the road, he’d usually see Justin at the course by late-morning.

Mike has been his son’s only instructor, but he intentionally took a laissez-faire approach with his son. Setup, plane and path were their focus, Mike said. Seawell credits Mike for “letting this be Justin’s journey.”

“I tell so many of my students that I’ve spent so much more time with you than I have with Justin,” Mike Thomas said. “I teach him very little. I always did teach him very little. I told him when he was 8 or 10 years old, ‘You know where I’m at if you need help, but if I’m teaching I may only have five minutes to give you.”

It’s an approach that made Justin self-reliant, and one that they still take today, even as Justin competes against the world’s best.

“I’ll play four holes and I’ll be hitting it terrible. I’ll (say), ‘Hello, what am I doing?’” Justin said. “He’ll say, ‘You didn’t ask me.’ I’m like, ‘I thought you’d get the hint when I’m re-teeing on every hole.’”

Justin developed a simple, on-plane action that allows him to squeeze the maximum power from his 5-foot-10, 145-pound frame. He’s 17th on TOUR in driving distance (302.5 yards). Matt Killen, a swing instructor on TOUR and family friend, tells enquirers that Justin’s power comes from “efficiency and solidness.”

Bill Haas was impressed after they played in the final group at the Humana Challenge. “Wow, what a player he is. … I wish I was 21 again, watching him swing,” Haas said after his victory.

Justin coils slowly on the backswing and pauses momentarily at the top before unleashing on the ball. He’s swung hard since he was young to compensate for his small frame. His aggressive downswing also is a byproduct of his competitiveness.

“If a guy was hitting it farther than him, I think he’s the type who would say, ‘I’m going to hit it where he hit it.’ He was not going to be denied,” Seawell said. That characteristic also made Justin a quick study.

“He’s not going to do something two times in a row that is detrimental to him or his game,” Seawell said.

Mike recalls the 2009 Wyndham Championship. Justin was going to miss the 54-hole cut, but had to complete two holes after a rain delay. Justin made a tricky sand save on No. 8, his second-to-last hole, then birdied the final hole. The finish brought tears to Mike’s eyes.

“I was bawling like a 12-year-old,” Mike said. “The fact that he took that much pride in what he was doing at 16 years old. I would’ve taken a couple bogeys and headed down the road.”

Mike jokes that the family's playing ability skipped a generation.

Before Justin, Paul was the best player in the family. He played in the 1962 U.S. Open at Oakmont, missing the cut in what would be Nicklaus’ first major victory. Paul tied for 15th in the 1983 U.S. Senior Open at Hazeltine.

“He’s told me the same stories a million times, but I never tell him to stop,” Justin said. “I keep all his voicemails.”

Paul got started in golf “the way we all did in those days.” He was 9 or 10 years old when he began caddying at the public Avon Fields Golf Course in Cincinnati, then began working as a club professional. He was the head pro at Zanesville (Ohio) Country Club for 26 years, and at 83 years old still gives the occasional lesson.

“His dad nor I really pushed (Justin),” Paul Thomas said. “We more or less answered questions. I would say the most help I ever gave him was playing with him and talking to him.

“His dad is his only teacher, and that’s the way it should be.”

Golf is a family affair for the Thomases, after all.