Little 8-year-old Sophia Caneiro was a devoted Girl Scout who loved the Yankees and baking with her mom and nanny.

Her brother, Jesse, 11, was a wise-beyond-his-years history buff who could carry on a conversation about current events with just about anyone.

They were the pride and joy of their parents, Keith and Jennifer Caneiro.

But their bright and promising lives were barbarically cut short on Nov. 20, when both were slain with their parents at their million-dollar mansion in Colts Neck, NJ, in a quadruple homicide that has rocked the quaint Monmouth County town and has left Keith’s older brother and business partner, Paul Caneiro, behind bars.

Jennifer frequently hosted family holiday parties at her and Keith’s sprawling modern mansion, according to an obituary posted online by the Holmdel Funeral Home in Holmdel, NJ.

The 45-year-old mom was a graduate of the University of Albany and relished spending time with her family, as well as working out and relaxing at the beach.

The Caneiros lived a quiet life with their dog, Sydney, in the bucolic town and loved escaping to their home in Greece.

Their comfortable lifestyle was made possible by Keith’s work — which, prosecutors allege, ultimately cost him his life.

The Caneiro brothers were business partners in two IT firms — Square One and Jay-Martin Consulting — both based in Asbury Park.

With an undergrad and master’s degree from Columbia University, Keith brought the brains to the family business. His obituary on the funeral-home site identified him as the CEO of Square One, and reports have said Paul was his first hire.

The 50-year-old dad was a sports fan and avid reader who devoured “three or four books in a week,” the obit said. He worked out down the road from his home at Aspire Fitness.

“He was an altruistic person who would help everyone and anyone who needed his assistance,” the obituary read.

On his Facebook page, Keith described himself as a foodie who “really loves veal and pizza.”

Keith and Paul had been in lockstep throughout nearly all of their adult lives. Both grew up in Brooklyn, moved to Staten Island, where they each met their wives, and then settled down in suburban New Jersey.

Both Keith’s Facebook page and that of Jennifer, his wife of nearly two decades, were loving tributes to their two children, filled with photo after photo of Jesse and Sophia throughout the years.

Both kids attended Conover Road Elementary School, where Jennifer was an active member of the Parent Teacher Organization.

A third-grader, Sophia partook in Girl Scouts and ice skating, excelled in her “ninja” classes and did gymnastics. Her favorite team was the Yankees.

“Sophia was a vibrant, enthusiastic and precocious girl who enjoyed the arts,” said her online obituary, which included photos of the girl grinning in magenta lipstick and showing off a project at school. “Her positive energy was contagious.”

Jesse was in the fifth grade but acted far more mature as a budding historian.

“He excelled in history, especially WWI and WWII, and he could have a conversation with anyone about current world events,” his obituary read.

The boy was obsessed with the latest technology and wanted to learn everything about the newest computers, phones and watches, the tribute said.

Jesse also loved to play the popular online video game “Fortnite” and build with Lego. A recent photo showed him as a handsome young man — the perfect amalgamation of his mother and father.

All four of the Caneiros’ obituaries list, among other relatives, Paul Caneiro, 51, as a surviving family member — even as he sits in Monmouth County Jail on murder, weapons and arson charges that could put him away for life.

The Caneiro family will be laid to rest Sunday afternoon at the Holmdel Funeral Home, with a memorial scheduled in the early afternoon and a funeral service to follow.

Members of the Caneiro clan, including a third brother, Corey, have not publicly commented on the tragic turn of events.

Efforts to reach surviving family members by The Post were unsuccessful.

“The family is grieving at the moment. We have no comment,” said a woman who answered the door at the Staten Island home of Cesar Caneiro, the father of Keith, Paul and Corey.

Prosecutors charge that Paul, driven by a financial issue tied to his and his brother’s business, gunned down Keith outside the Colts Neck mansion and then gutted Jennifer, Jesse and Sophia inside before setting a slowly burning fire in the basement.

The murders have shaken even the most seasoned prosecutors.

“This is one of the most brutal cases I’ve seen in my experience here,” Monmouth County Prosecutor Christopher Gramiccioni said at a press conference Thursday in announcing the murder charges against Paul.

Paul was initially charged a day after the slayings with arson — for allegedly setting fire to his own home about 10 miles away in Ocean Township.

Prosecutors allege that he did so, with his wife, Susan, and adult daughters, Katelyn and Marissa, inside, to make it appear as though the entire Caneiro family was being targeted.

No one was injured in that fire, and the home did not appear to have sustained any significant damage.

Through his lawyers, Paul maintained his innocence.

Katelyn’s friends launched a GoFundMe page to raise money for her and “the surviving Caneiro family,” saying they “do not have a roof over their heads, clothes, winter coats, dog food for their dogs, even toothbrushes.”

“Not only are they dealing with the tragic loss of their family, they also have nothing and nowhere to go,” said the page, which had garnered more than $9,800 as of late Friday. “They have lost their home and all of their belongings. The news doesn’t cover the fact that the family is on their own right now.”

It added, “They have no funds to support any rebuilding of their lives, even just for the time being of having basic necessities.”

The fundraiser also acknowledged how close Paul and Keith’s immediate families were with one another.

“As Katie Caneiro’s best friends from college/home,” the page said, “we have watched over the years as the family helped care for the children, had joy-filled holidays, and attended exciting milestones and school events with Keith, Jen, Jesse, and Sophia.”

Additional reporting by Nick Fugallo