On Dec. 6 of his rookie season with the Boston Celtics, the same day he scored 17 points and grabbed 10 rebounds in a win over the Dallas Mavericks to lift his team to a league-best 22-4 record, 19-year-old Jayson Tatum became a dad. He named his son Jayson Christopher Tatum Jr., nicknamed Deuce. The baby was perfectly healthy, and his eyes are two different colors: one brown, the other grayish blue. Over the course of the season, Celtics fans came to recognize the little guy at TD Garden. Tatum's mother, Brandy Cole-Barnes, who moved from the family's home in St. Louis to Boston after her son was drafted, would bring Deuce to every home game. "Is that Deuce?" fans would ask, at the arena and all around town, then coo at him.

A few weeks ago, at 11 months old, Deuce took his first steps. At first it was slow going, boosting himself up with furniture. But by now he's a legit walker. Tatum counted his kids' steps, and the other day he proudly announced in the Celtics locker room exactly how far his son can walk: "He can take like 18 steps in a row!"

"I didn't know what to expect," Tatum told me recently, talking about both his first year in the NBA and his first year being a father. "First year in the league, that's a lot of challenges in itself, plus I have a kid. So it was a busy year last year for me. Watching Deuce grow up, it's really mind-blowing. I can't believe it. He's growing up so fast."

The same thing that can be said about the son can also be said about the father. A few minutes into Tatum's NBA career last season, his teammate, Gordon Hayward, suffered a gruesome leg injury that ended Hayward's season and jarred his teammates. By the time Hayward was being carted off the floor, Tatum's role as a rookie had changed. He went from a player who could slowly be integrated into his team's flow to an integral piece for a team that was expected to contend in the Eastern Conference.

And he responded. From that very first game, amidst all the hype around opening night and all the emotions around Hayward's injury, Tatum looked like he belonged. He got a double-double in his first NBA game with 14 points and 10 rebounds. He averaged 13.9 points and 5.0 rebounds in 30.5 minutes per game, and his 58.6 percent true shooting percentage ranked second among rookie wings who played rotation minutes. Unlike most rookies, Tatum got better as the season went on. He averaged 18.5 points per game in the playoffs. Tatum finished third in Rookie of the Year voting.

So far this season, his production has increased across the board. As Boston has struggled offensively all season, Tatum, whose Celtics will take the court next against the New York Knicks on Wednesday (7:30 p.m. ET -- watch on fuboTV with the NBA League Pass extension), has been one of Brad Stevens' most reliable options.

"This is what I've always wanted," Tatum told me. "Couldn't be any happier where I am in life."

But what Tatum's mother has always preached is the social responsibility that comes with athletic stardom.

Cole-Barnes had Jayson when she was 19, and she raised him as a single mom. There were times when the utilities were turned off, when bills went unpaid for months, when mother and son had to share a bed because they couldn't afford enough furniture, when they nearly got foreclosed upon in their two-bedroom, 900-square-foot house in St. Louis' University City. Tatum's dad was always around, and they always had a great relationship, but it was Cole-Barnes who raised him. And Cole-Barnes never wanted to rely on others, so she modeled self-sufficiency from his infancy -- literally. She gave birth during spring break from college, and then was back in class the next week. Later, as he grew into a toddler and then a little kid, she brought Jayson to classes with her, all through undergrad and law school and business school.

Their plan was always to give back to the community when they had the means. He donated a new floor to the St. Louis' Wohl Recreation Center in 2017. He did a back-to-school initiative in St. Louis where he filled 400-some backpacks with school supplies to hand out to schoolkids. The mayor of St. Louis even proclaimed one day this past summer "Jayson Tatum Day."

Tatum and his mother appreciate that their difficult journey led them to an incredible place, and that not all single moms end up in such a great place. That's why their hearts remain with helping single mothers; the newly formed Jayson Tatum Foundation is gearing up for an initiative to help single moms. They've partnered with a shelter for single moms and their children to help with things like utilities and childcare. Instead of gifts for Deuce's first birthday, Tatum and his mother are asking people to make donation to a St. Louis orphanage.

Their biggest initiative is coming soon: They are planning to purchase houses in St. Louis, rehab them, get them up to code and then allow single mothers and their children to live in them rent-free.

"I used to tell him the whole time when he was in high school and college to enjoy everything about it because once it got to this level, it would go to be a business," said Cole-Barnes. "That has certainly been the case. It's been crazy, it's been really busy. Some people have an unrealistic expectation of what this life is really like, how stressful it can be. We're blessed, but there's a lot that goes on."

Cole-Barnes is Tatum's rock. She helps manage his business affairs, and she lives in the same condo building as Tatum so that when he's on a road trip, she can watch Deuce. Meanwhile, she still holds her day job, a lawyer who does compliance work related to Medicare and Medicaid. (Only a single mom could successfully juggle all this.)

"We talk every day," she said. "I just try to keep it 100 with him at all times, remind him what he's worked for and how far he has to go. Getting into the league was not the end goal. I know he's blessed and he's had a great opportunity. But he really hasn't done anything yet."

One of the things he really wants to focus on the next offseason is the housing initiative for single moms. His first offseason was hectic, filled with obligations. He threw out the first pitch at a St. Louis Cardinals game. He put on free basketball clinics for children. He worked out with Kobe Bryant. But the next season, once all the legal I's are dotted and T's are crossed for his foundation and the housing initiative, he'll focus on that more. The first house that Tatum and his mother want to turn into a home for single moms is that same two-bedroom, 900-square foot house where Tatum grew up.

"That's my life," Tatum told me. "That's how I grew up. I was fortunate enough to make it to where I want to be. There could be other kids as talented or more talented than me in whatever they want to be, but don't have the resources to pursue their dream. Maybe they have to get a job instead to help their mom with the bills. But you can take that away and both of them can focus on what they want to do in life."