Timberwolves star big man Karl-Anthony Towns celebrates his 21st birthday Tuesday, a final signpost to adulthood that teammates Andrew Wiggins and Zach LaVine already have passed.

In Sunday’s 125-99 victory over the Los Angeles Lakers, Wiggins became the youngest Timberwolves player to score at least 40 points in a game — younger than Michael Beasley, Steph Marbury, Kevin Love, Al Jefferson — with a 47-point night reached when he was 21 years and 264 days old.

Together, all three young men have played on something of a national stage since they were in high school, if not earlier. They are beyond their years already on a hardwood court and yet, as Timberwolves coach Tom Thibodeau reminds, still have far to go both on and away from the floor now that they can all drink legally together.

“We all came into the league at the same age,” Wiggins said about being 19 and NBA-bound. “We’re all trying to accomplish the same goal, on the same journey together every step of the way. We’re getting older. We feel it.”

Before he celebrates a milestone birthday both with his family and by playing Charlotte at Target Center, Towns spoke about feeling old personally and young professionally, all at the same time.

“I am old,” Towns said. “It’s a lot of experience I’ve had. I’ve been fortunate to have 21 years on this Earth, but I feel like I’ve lived about 60 years.”

And yet, he and many of his teammates, particularly Wiggins and LaVine, have not yet grown into their bodies or their games, at least not as they someday will.

“We still are young,” Towns said. “This is my second year. It’s their third years. We still have baby legs in this league. We’ve all had to grow up fast. The life that we live, the lights are on us. It has made us grow up at a more exponential rate.”

They are probably the most precocious threesome since Kevin Durant, Russell Westbrook and James Harden all came up together for three seasons in Oklahoma City before the Thunder traded Harden to Houston, primarily because it decided it couldn’t afford to keep him.

Future Basketball Hall of Famer and then-teammate Kevin Garnett spoke to all three players last season. Speaking from personal experience with Marbury long ago, Garnett urged them to avoid “ego,” appreciate playing with such talented teammates and reminded them “younger days are days you can’t get back.”

Whether there always will be enough featured roles, enough shots, enough money for everybody remains to be seen. But that will come down the road.

“We all like each other,” LaVine said. “We’re all best of friends. We hang out with each other all the time. We haven’t really ever talked about not being together.”

As 20-year-olds, they collectively averaged more points among the three of them than the Thunder’s trio did at the same age, although both Westbrook and Harden didn’t play an NBA game until each was 20.

Thibodeau admits his three young stars are accomplished on one end of the floor and still lacking at the other. He has challenged them to commit themselves to learn to be great two-way players together.

“We need more,” Thibodeau said. “Offensively, it’s fine. Defensively, we need more, a lot more.”

Wiggins will turn 22 in February, LaVine in March.

“Every once in a while our teenage personalities still come out,” LaVine said, “but I think we’re maturing.”

Towns, in turn, celebrates his 21st birthday on a Tuesday that he promises will be like any other day, even with his family from New Jersey in town to gather around him.

“I get to play basketball on my birthday for the second year in a row, so I’m blessed and honored,” said Towns, who played against Memphis on his 20th birthday. “It’s always fitting how basketball has taken over my life, so I’m cool with it.”