With the important exception of children who need protection from an abusive or negligent parent, "shared parenting should be the norm for parenting plans for children of all ages, including very young children," said Linda Nielsen, a professor of adolescent and educational psychology at Wake Forest University.

It's difficult to believe that, in 2017, this even is a question. But statistics show that mothers still are awarded full physical custody of children in more than 80 percent of court-ordered child custody cases.

One big reason for the inequity is a decades-long belief by judges and others that conflict between divorcing parents (which is to be expected at this difficult passage) will cause too much stress for children. Those wary of establishing shared parenting argue that it places children in the middle of disagreements, pressures them into loyalty conflicts or forces them to side with one parent against the other.

Their thinking is that it's better to formally place the children in Mom's household for stability and let Dad parent one night a week and every other weekend.

In a new study, Nielsen re-examined this notion — with surprising results.

"The role of conflict has too often been exaggerated and should not be the determining factor in child custody decisions," said Nielsen, who has researched father-daughter bonds for more than 25 years.

Even the concept of conflict is problematic, Nielsen said, "because it is difficult to define or to assess reliably, in part because parents sometimes exaggerate or provoke conflict to 'win' sole custody."

In addition, conflict typically subsides within the first few years after separation, but custody decisions often last a childhood.

Nielsen reexamined 44 previously published studies on divorce conflict and its impact on children. She set out to answer four questions:

• To what extent do less conflict and a cooperative co-parenting relationship benefit children?

• Do children whose parents are in legal battles or who take their custody disputes to court have worse outcomes than children whose parents reach a custody agreement without high legal conflict?

• If children live with each parent at least 35 percent of the time in a shared-parenting scenario, are the outcomes significantly better if their parents have little to no conflict and work closely together as a friendly co-parenting team?

• And, do parents in shared arrangements have significantly less conflict and more communicative, cooperative co-parenting relationships?

She did not find strong support for the belief that high conflict and poor co-parenting mean poor outcomes for children.

What she did find is that the quality of the parent-child relationship, with both the father and the mother, trumped everything else.

"Forget that it's divorce," she said. "Think about growing up in a married home. Of course, it bothers kids when their parents quarrel. Conflict does matter. But what we're saying is that the quality of your relationship with your parents matters a whole lot more than the parents' relationship with each other."

Her study was published in Psychology, Public Policy, and Law, a journal of the American Psychological Association.

To truly help families move forward with the best interests of children front and center, Nielsen believes, the focus should be on developing programs and policies that strengthen the child's relationship with each parent and reducing children's exposure to conflict, "rather than assuming that joint physical custody is not an option."

There is growing support for that sentiment.

Children in shared custody arrangements "do considerably better on every measure, from school success, to fewer teen pregnancies and drug use, to having optimism for the future," said Dr. Ned Holstein, a public health practitioner and founder of the National Parents Organization (natioalparentsorganization.org), which aims to reform family court practices.

Holstein noted that in the past year, Missouri and Kentucky have passed "excellent shared parenting legislation," following states including Utah, Arizona and Alaska.

"If you want to hasten the process of healing, or at least tolerance, the worst thing you can do is declare one person a winner and one person a loser," he said.

"You're both winners. You're both going to be parents. That will actually diminish conflict."

gail.rosenblum@startribune.com 612-673-7350 • Twitter: @grosenblum