THE PARENTS: Betsy Castaldi, 36, and Rick Castaldi, 68, of Center City.
THE CHILD: LilaBella Elizabeth, born Jan. 21, 2017.
HOW THEY MOVED IN TOGETHER: Stealth-style, with Betsy and her mother carting clothes and artwork to Rick's place while he attended a Phillies game with Betsy's father.

When LilaBella was born, she became cousin number 44 on Rick's side of the family.

Not that anyone's counting.

When Betsy and Rick met — he was the guy alone at Tria in a Semester at Sea T-shirt, and Betsy (at the bar with her then-boyfriend) was an alumna of the program—neither one dwelled on the three-decade age difference.

Instead, they talked excitedly about their common turf: Both had traveled on three-month Semester at Sea voyages, crossing six time zones and visiting 17 countries.

In fact, Rick had just returned days earlier from his first Semester at Sea trip as a professor. "My mind was still in the Mediterranean," he recalls. "I like adventure," Betsy says. "I think that's what really drew us together."

But Betsy had that boyfriend, and Rick was soon leaving to teach MBA seminars at San Francisco State, where he was a tenured professor. They didn't meet again until the following May, at a Philly reunion of Semester at Sea faculty and alumni. By then, the boyfriend was out of the picture.

Initially, Rick fudged his age: He was 61 when the couple met but said he was "in his 50s." By the time Betsy learned the truth — she glimpsed his driver's license one evening — she was too smitten to care.

"I was concerned about how [the age difference] would play out with Betsy's family," Rick says. "But they were wonderful, accepting of me from the very beginning." It helped, Betsy says, that an aunt of hers had married a man several decades older than she was.

Anyway, Betsy's mother was more concerned about her plan to quit her sales job and accompany Rick on another round-the-world voyage in 2011. It was a test: four months cohabiting in a ship's cabin (admittedly, a luxe one, with a balcony), getting lost in the labyrinthine streets of Medina, Saudi Arabia, groping to communicate in unfamiliar languages.

"I realized during the voyage how meaningful this relationship was," Rick says. The spring after they returned, he invited Betsy back to Tria, stammered as he ordered wine and snacks, then dropped to one knee beside her chair. The bar manager uncorked champagne.

They marked their marriage three times: a legal wedding in Jamaica, a reception at home, then a Catholic church ceremony once Rick's first marriage, a short-lived union with his high school sweetheart, was annulled. Betsy had her mother's 1970s-era dress remade and wore it for all three occasions.

Rick had spent his life around children; As the youngest of 11, he became an uncle for the first time at the age of 5. And 25 years of university teaching had left him at ease with young adults.

"I always assumed I'd have kids. But I was pretty consumed with the academic experience and challenges," he said. When Betsy raised the question of children, he had the perfect answer: "Bets," he said, "I always thought I would have children. Let's try."

Rick knew that was a gamble: Would they be able to conceive, given his age? And if they did have a baby, would he be around to see that child graduate from college, get married, have children of her or his own? "I have to come to grips with the limits I'm subject to," he says. "But it never entered my mind that I shouldn't do it because of the age difference."

It took 2½ years to conceive — timing their attempts so diligently that it felt like a job, Betsy says, then seeking fertility counsel and trying intrauterine inseminations to boost their chances.

They were so accustomed to seeing negative pregnancy tests that they didn't recognize the plus sign that appeared one morning in 2016. Betsy jumped up and down in the bathroom; Rick snapped a picture of the drugstore stick.

Betsy, who had done fertility meditation, yoga, and acupuncture before becoming pregnant, planned a natural birth with midwives and a doula in attendance. As she neared her due date, she occasionally invited close friends to touch her belly. "Feel her little butt; it feels so hard!" she'd say.

At 38 weeks, the midwife delivered bad news: That was no butt; it was a head, which meant a breech baby and a scheduled C-section.

LilaBella was born Jan. 21, the day of women's marches around the world. Her parents watched some of the coverage while they waited; finally, Betsy was in the OR and Rick was clad in scrubs, masked, and watching as a doctor pulled their daughter from the womb. "I just broke down and cried," he recalls. "I couldn't breathe. I had to leave the room to blow my nose."

Then they brought LilaBella home, to the house with the yoga-room-turned-jungle-theme nursery and the jolting urgencies of parenthood. Betsy hadn't bought a breast pump; "I thought, 'I'll be home with her; why do I need one?' " She'd planned to use cloth diapers until faced with the reality of changing them 10 times a day. The concept of  "sleep training" seemed bizarre: "You have to train them to sleep?"

"My age helps me cope with the stresses and uncertainties of fatherhood," Rick says. And from LilaBella's point of view, "Her dad's her dad," Betsy says. "She doesn't know he's older." What she knows is that her father is cuddling her at breakfast, that her mom is talking in the Daisy Duck voice that always makes her laugh.

Betsy remembers a dream in which Rick's Irish mother, whom she never met, returned from the dead to assure her: "LilaBella is from my people. She's old stock. You have nothing to worry about."

Meanwhile, they are marking moments, not years: How, just the other day, LilaBella figured out that her hands work better in tandem. How she squeals in perfect imitation of a mouse. How her voice, stronger each day, means her lungs are growing. "The magic in the small things almost overwhelms me," Rick says.