PHOENIX — During Super Bowl week, coaches named Belichick and Carroll set about preparing for one of the biggest games of their lives.  One stayed out of sight, dodging interview requests, preferring instead to focus on the New England Patriots’ preparations.  The other paced the floor at media day, checking on his players and talking passionately about his team’s resolve. He said he was especially proud that when the Seattle Seahawks trailed the Green Bay Packers, 16-0, in the N.F.C. championship game, nobody in the organization believed they were out of it.  But these were not the football masterminds Bill Belichick and Pete Carroll, who have their teams on the cusp of another Super Bowl title. They were their sons and assistants, Steve and Nate, whose demeanors eerily resembled their fathers’.  Steve Belichick, 27, helps evaluate opposing teams, among other things, as a third-year Patriots coaching assistant. He has an imposing build and long, blond hair. Tight end Tim Wright is one of four players on New England’s roster from Rutgers, where Steve was a long snapper and long-stick midfielder in lacrosse, and occasionally acted as his barber there.  Players describe Steve Belichick as easygoing but quiet — except before kickoff, when he performs a head-butt with defensive back Duron Harmon.  “Duron has a helmet on, and Steve doesn’t,” cornerback Logan Ryan said, smiling. “It just shows how into it he is, and that he’s just one of the guys.”  That is, unless someone hears him before seeing him.  “It’s funny, they sound a lot alike,” defensive back Devin McCourty said of the Belichicks. “Steve’s one of the players almost. You can always talk to him, you can hang out with him, but sometimes, if you have your back turned and you hear Steve talking, you might freeze up for a second because you think Bill’s behind you.”  McCourty added, “I think the first thing you notice with Bill is that no one has it easy, and he certainly doesn’t cut Steve any slack.”  Nate Carroll, 27, is the Seahawks’ assistant wide receivers coach. He joined the organization in 2010, after earning a psychology degree from Southern California, where his father coached until 2009.  “When I was in college, he said, ‘Just make sure you keep your name out of the papers; just understand what the consequences could be,’ ” Nate Carroll said, referring to his father. “So I always had that on my mind. I tried to stay out of the way.”  The Seattle Seahawks coach spoke on Wednesday about what it is like working with his son  Of course, he did not always get off so easily.  “That last semester was the weirdest one for sure because, O.K., now he’s leaving and I’ve kind of got to be like, ‘Hey, sorry everybody,’ ” Carroll said.  There are two players from U.S.C. on the Seahawks’ active roster, and to them, Nate is just one of the guys. “You don’t want to mess with the coach’s son,” linebacker Malcolm Smith, a former Trojan, said jokingly. In fact, Nate fits in so well that linebacker Mike Morgan asked, half-serious, “Why would anyone write a story about Nate?”  “You don’t see them that often together,” Morgan said of the Carrolls. “I know they go out and play basketball every once in a while. But you don’t really see that relationship in the building. He’s just another coach on the staff.”  His first two years with the Seahawks, Nate Carroll worked on the defensive side of the ball. For the past two, he has worked on offense. Asked about the reason for the switch, he said, “Bill Belichick.”  “My dad called Coach Belichick about it, saying he had this feeling that he had his coaches switch from offense and defense to get a feel for the whole game, and he told me, ‘I think I’m going to try to do the same thing with you,’ ” Nate Carroll said.  Steve Belichick, who was named after his grandfather, a former N.F.L. player and college coach, played lacrosse at Rutgers for four years but did not take up football there until his senior year, when he was a walk-on.  “He could have easily just wrapped up his Rutgers career as a successful lacrosse player, but he wanted to go out there and help out the football team,” Ryan said. “It shows you a lot about how much he cares about football and what he wants to do.”  Ryan continued: “Growing up around the game, it’s easy to not want to do it anymore because you’ve been around it so much. But he has a passion for it. People don’t see the Steve that pulls in at 5 a.m. every morning and leaves late at night. He’s there longer than us.”  Bill Belichick said he was cherishing the time he spends with his oldest son, even if he preferred to keep the father-son relationship professional around the office.  “Stephen was pretty much away for six years with prep school and college lacrosse, and then a year of football with Rutgers,” Belichick said. “So it’s great to have him back, see him on a daily basis and be able to work with him.”  Pete Carroll said it was a “treasure” to work with his son.  “To compete with your son, really, at this level, to battle and to work day and night to try to figure out ways to try to win football games, and you’re doing it with those that you love, it just makes it a cherished time for us,” he said. “More so maybe for me than him, but I feel very fortunate that we get to do that together.”  “We talk about so many different things, from football to life,” he said. “Football is about X’s and O’s some of the time, but there’s so many personalities, so many people that you have to deal with, that I try very hard to be humble, to be mindful of the people around me and what it means to affect people in a positive way. I don’t know that he’s ever given me the advice, in terms of words like that, but being around him, that’s what I’ve learned.”  On Sunday, the sons will meet in the Super Bowl. Perhaps one day, they will meet there again, as head coaches.  “I believe if you don’t set your sights high enough, you might never get there,” Nate said. “I need to keep my horizons as broad as possible. I’m not going to make any predictions or anything; I’m just going to keep moving along. But I’ve got my sights set pretty high.”  A version of this article appears in print on February 1, 2015, on page SP6 of the New York edition with the headline: When Coaching Is the Family Business . Order Reprints| Today's Paper|Subscribe
The sons of coaches Bill Belichick and Pete Carroll are valuable assets to their teams as assistants and have high aspirations in the N.F.L.