Everyone haunted by the disappearance of 8-year-old Relisha Rudd has the same question.

Why was the second-grader allowed to live with her mother, Shamika Young, a 27-year-old residing in a D.C. homeless shelter with four kids, posting Facebook photos of herself and her boyfriend “high as kites,” whose daughter showed up to school hungry and dirty and who crossed paths with city social workers more than once?

Why wasn’t Relisha removed from that unstable environment long before her mother handed her over to a shelter janitor, Kahlil Malik Tatum, who is believed to have killed his wife before he killed himself?

The answer is complicated, and it involves a woman named Banita Jacks. Jacks also had four kids. She killed them and lived with their mummifying bodies for months before an eviction in 2008 revealed the horrors of the family’s decline. She is serving a 120-year sentence.

That family fell through every possible safety net in the city: schools, social workers, police, neighbors, health-care workers. No one took action. And then everyone took action.

Banita Jacks in a 1999 booking photo from Charles County. In 2008, she was charged with four counts of first-degree murder in the deaths of her four daughters, ranging in age from 5 to 16. (AP)

After the bodies were found, the District’s Child and Family Services Agency was inundated with calls from good Samaritans reporting all their bad-parent suspicions. Social workers couldn’t keep up at a time when they were already under fire for negligence.

“When in doubt, pull them out” became the CFSA mantra, leading to one of the highest child removal rates in the country. Social workers were terrified they’d miss another Banita Jacks.

The city’s foster care system was unprepared and quickly cratered. I remember talking to social workers who couldn’t go home to their families because they were still driving around with frightened, trembling children who had just been pulled out of their homes but had no available foster home to go to late at night.

The majority of children who go into foster care are there because of neglect, not abuse, with poverty the root cause. And study after study shows that most children do not fare particularly well in foster care.

“The nuclear secret of child welfare is that most of the children in foster care should not be there,” said Matt Fraidin, a law professor at the University of the District of Columbia David A. Clarke School of Law, whose law clinic students handled scores of foster cases, some with horrifying narratives of kids taken from their homes after a report only to be returned a month later when no wrongdoing was found.

“Most of the children in foster care are harmed more than they are helped by being taken from their families and by being kept in foster care for too long,” he wrote.

This isn’t a commentary on foster parents. There are some fantastic foster parents I’ve met who nurture and repair abused children or go on to adopt them and create loving families. But for most children, the trauma of being removed from their parents and placed with strangers trumps the less-than-ideal conditions in their homes.

In fact, Relisha’s mother is the product of the foster care system in Virginia, where she bounced from home to home from the time she was 6 until she turned 18. Once she aged out of the foster system, Young returned right back to the family she was removed from, as do many other foster kids. She obviously didn’t learn much about how to be a parent before she had Relisha at 19, followed by her three younger brothers.

On her Facebook page, Young bragged about having her kids in expensive, Helly Hansen jackets and Air Jordan shoes even as they were living in a homeless shelter. In her world, this was evidence of a caring parent.

Relisha was almost 2 years old in 2007 when social workers first investigated signs of abuse. Police were called but eventually concluded that no assault had occurred. That was before the ghost of Banita Jacks haunted the system, and the question remains as to whether Relisha fell through the same safety net that lost Jacks’s daughters that year, too.

By the time Relisha’s family was flagged by social workers again in 2010 and 2013, the department had done an about-face, working to keep struggling families intact rather than removing children from their troubled homes.

So does that mean that Relisha’s disappearance and probable death are the tragic by-products of a bad philosophy? No way.

City social workers have been performing far better in recent years. The department is still being scrutinized by a court monitor. But all the monitor’s reports show that cases of abuse have gone down and that investigations are completed faster and are more thorough. Social workers now have teams to review cases for removal, so it’s not just up to one, quick doorstop decision by a single social worker.

Will there be a temptation to go back to removing all the possible Relishas from their troubled homes and putting them into foster care? Yes, but I believe the agency learned from the last overcorrection and won’t do that again, no matter how much everyone wants to make up for what happened to Relisha.

The hindsight that would tell social workers to remove Relisha won’t save her, but it may save her three brothers, who have been placed in foster care.

This case puts into sharp focus how fragile these families are, how difficult and potentially disastrous each decision about whether to keep a family together can be. Taking care of the city’s vulnerable children is so fraught. And often there is no such thing as a do-over.

To read previous columns, go to washingtonpost.com/dvorak.