STONY BROOK, N.Y. — CJ Trenkle had been hooked by Stony Brook men's lacrosse long before joining the program.

Without interruption from 2005 through 2011, Trenkle's brothers played for the Seawolves.

"My parents and I pretty much went to every game — even traveling-wise," Trenkle said about that seven-season span. "I would say in that span we legitimately missed two or three games. So, from the age of 7 to 14, I lived Stony Brook lacrosse. And then I started getting recruited here."

The 22-year-old Trenkle, a Commack native, now enters his senior season as a defenseman and captain with the Seawolves.

And, like brothers Bobby and Timmy before him, Trenkle is wearing No. 20 — although it took a couple of years to secure in his case.

When Trenkle arrived on campus in the fall of 2016, senior Mark Ellis had the number. Ellis ended up redshirting that spring and then transferred out the following fall. But, by then, Trenkle's No. 37 gear already had been ordered for his sophomore year.

Trenkle finally was able to switch to No. 20 as a junior a year ago. It proved meaningful for him — and, even more so, his family.

"Twenty is a big family number," Trenkle said. "Everything in the house is 20. We were all 20 growing up. I was 20 because they were 20. I don't know where the number came from. Jokingly but seriously, my parents were like, 'You need to get 20, because all of our apparel, all of our gear from when they were there, is 20.'

"The first time I wore 20 for a fall game, my parents took a picture and sent it to my brothers. They were like, 'Here we go! Twenty is back.' It was special. Even all of my friends knew the deal with 20. When I came in the locker room the first day and 20 was on my sweatshirt, it was pretty exciting."

The allure of playing at the same school as his brothers attracted Trenkle to Stony Brook. But the youngest of the three brothers also was gratified that he was recruited by the program on his own merits rather than primarily based on bloodlines. A different coaching staff signed Trenkle than the staff that had been in place when his brothers played several years earlier. Stony Brook, in fact, was the first program to offer Trenkle a scholarship.

The 5-foot-10 Trenkle appeared in only four games apiece as a freshman and sophomore, but started all 15 games for the Seawolves last season. The leap in playing time as a junior partly was due to the graduations of Tyler Anderson and Kyle Abdellatif. But Trenkle also seized the opportunity by polishing his defensive technique and bulking up in the weight room. He swelled from 170 pounds at the end of his sophomore year to a current weight of 185.

"It was a matter of me looking at myself and knowing what I needed to work on," Trenkle said. "Defensemen are usually 6-foot-plus. Me, having my smaller size, I knew I had to put a huge emphasis on being stronger. I couldn't afford to not be strong. I also watched a lot of film of myself to make sure I was doing all of the little things that I could to give myself an advantage. It ended up working out in the end."

Trenkle also has excelled in the classroom.

He arrived at college with 20 credits already completed thanks to AP coursework at Commack High School. And Trenkle was able to graduate from Stony Brook in three years with bachelor's degrees in economics and applied math. This fall, he began coursework toward a master's in economics. He plans to remain at the university next academic year to complete that degree, even though this is his final season of playing eligibility.

"He's one of those rare guys who can lead by doing and lead by communicating," first-year head coach Anthony Gilardi said. "He takes the young guys under his wings and shows them how to do it the right way. And he's out there working hard every single rep. To graduate in three years, and to be able to balance grad school, being captain of our team and a leader is pretty special."

Trenkle, knowing he was remaining at the school as a graduate student, actually chose not to participate in the university's main commencement exercises last May at LaValle Stadium, also home to the lacrosse team.

He did make one concession, donning the cap and gown to attend the department ceremony.

"I went there for my mom," Trenkle said. "She wanted a picture."

Bobby, who played for the Seawolves from 2005 through '08, now works for PIMCO Investment Management in Newport Beach, Calif., selling financial products to financial advisors.

Timmy, a Stony Brook player from 2008 through '11, and a former Long Island Lizards supplemental draft pick, also is in the financial services industry. He works on the stock-trading floor for Morgan Stanley in Manhattan. (Timmy wore No. 43 as a freshman at Stony Brook, when he overlapped one season with Bobby.)

And although Trenkle is the youngest of the three brothers, he may not be the last Trenkle to wear No. 20 for the Seawolves.

Bobby has a 2-year-old son.

"I don't know about here, but there definitely will be another Trenkle playing lacrosse," Trenkle said. "The second he was born, there was a mini-stick in his hand."