CHARLOTTE, N.C. — Seth Curry was a senior at Charlotte Christian School when he was reminded, loudly and in rhythm, of the near-impossible standard his older brother set.

During a road game in 2008, the opposing student section chanted, “YOU’RE NOT STEPH-EN!” Emboldened by the taunt, Curry responded with four straight three-pointers.

“He just held his chest out proud,” said Shonn Brown, who coached both Seth and Stephen Curry at Charlotte Christian. “He was like, ‘You’re right: I’m not Stephen, and I’m not supposed to be. This is who I am.’”

Many assume that Seth’s famous bloodline — in addition to having a two-time NBA MVP as a big brother, his father, Dell, is a former Sixth Man of the Year — would help him carve out a niche in the league, but he believes it has been just the opposite. His game is constantly measured against his sibling’s, and there is only one Stephen Curry.

Though the comparisons to Stephen don’t figure to stop anytime soon, Seth has quietly established himself as a bona fide rotation player. His invite to Saturday’s NBA Three-Point Contest at All-Star Weekend, where he’ll compete against Stephen in their hometown of Charlotte, wasn’t merely for a feel-good storyline. Seth ranks third in the league with a 3-point percentage of 46.5, more than two points better than Stephen’s.

“Regardless of what the narrative is or what people say about him, he just has supreme self-confidence,” Stephen said of Seth. “God blessed him with that personality for a reason in terms of him just being himself, understanding not just what kind of man he is, but what kind of basketball player he is. He obviously belongs in the league, and can do some amazing things.”

Off the court, the two brothers have few similarities. Seth is so introverted that he once refused to get out of his mother’s car when she drove him to a middle school dance. Stephen is outgoing and bubbly, the focal point of family gatherings without trying.

Basketball gave them common ground.

As soon as Stephen could walk, he was shooting his Nerf ball through a miniature hoop. It wasn’t long before Seth, who is 2½ years younger, joined Stephen. By elementary school, their Nerf battles had shifted to the full court behind their Charlotte home.

Because he was smaller and less experienced, Seth initially relied on tricks to compete in their backyard duels. But as he grew, in both size and ability, Seth stopped the gimmicks and won his share.

Those pickup victories gave him a self-assuredness that would prove vital years later. As he struggled to stick in the NBA, Seth took solace knowing that he had long held his own against perhaps the best shooter in league history.

That didn’t make his repeated setbacks any less frustrating, however. Scouts seemed to focus more on what he couldn’t do than what he could, and feedback often included a tie-in to Seth’s brother: You’re a good shooter, but you’re not as good as Steph. You’re not as big as Steph, and you don’t play with his joy.

All-Star W eekend Saturday: Skills competitions, including Steph and Seth Curry in the 3-point contest. 5 p.m. TNT Sunday: All-Star Game, including Warriors Steph Curry, Kevin Durant and Klay Thompson. 5:20 p.m. TBS, TNT

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After going undrafted out of Duke in 2013, Seth was waived three times and signed two 10-day contracts. While with Golden State’s NBA Development League (now G League) affiliate in Santa Cruz, he shared a backcourt with Mychel Thompson — Klay Thompson’s older brother — and, much to Seth’s chagrin, was labeled a “Splash Brother.”

In July 2015, after earning All-NBA Summer League first-team honors with the Pelicans, Seth signed a two-year, $2 million guaranteed deal with the Kings. The Warriors had made him an offer, but he didn’t want all the attention that would come with playing alongside Stephen.

Seth’s breakthrough came in 2016-17, when he averaged 12.8 points on 48.1 percent shooting (42.5 percent from three) in 70 games with the Mavericks. In a blend all his own, he flashed his brother’s step-back jumper and his dad’s catch-and-shoot ability.

Since missing last season with a stress fracture of his left tibia, Seth has emerged as the primary backup to Trail Blazers All-Star guard Damian Lillard. It should come as no surprise that two of his better performances — an 11-point outing on Dec. 27, and an 11-point showing on Wednesday — came against Golden State.

“I get a lot of interview requests about Steph, but I always remind them that I have another son in the NBA, and I’m just as proud of everything he’s accomplished,” Dell said. “He’s earned everything he’s gotten.”

Seth and Stephen have been each other’s biggest advocates since their elementary school days trading 3-pointers before the Hornets’ pregame warm-ups as Dell rebounded.

When Stephen married his childhood sweetheart, Ayesha, in July 2011, Seth delivered the best man’s toast. In May 2015, when Stephen told Seth during his MVP speech that the “sky’s the limit for you,” Seth fought back tears. Over the past year, Stephen — a father of three — has helped Seth, who has a 10-month-old daughter, Carter, with his fiancee, juggle work with parenthood.

However, no family bias would make him want to settle for a second-place finish at Saturday’s 3-point contest. Stephen and Seth grew up hearing a familiar edict from their mom, Sonya: “If you’re going to compete, you’re going to compete to win.”

“It’s going to be a lot of fun, I’m excited,” Seth said. “Hopefully, I can get the win.”

Asked whether he’d beat his little brother, Curry smirked and said, “Of course. Of course.”

Connor Letourneau is a San Francisco Chronicle staff writer. Email: cletourneau@sfchronicle.com Twitter: @Con_Chron