Nancy Gruver has championed the unique gifts of girls for close to a quarter of a century, as the mother of twin daughters, now 35, and as founder of Duluth-based New Moon Girls magazine.

So her recent advice to parents might take some getting used to:

We must let our girls fail.

When we step in to fix everything too quickly, we give our daughters the inaccurate and unintended message that they are “incapable of bouncing back,” Gruver said. “Failure in childhood is a powerful teacher.”

Gruver’s thinking evolved after talking with Jessica Lahey, author of the new book “The Gift of Failure: How the Best Parents Learn to Let Go so Their Children Can Succeed.”

Gruver went into the conversation with no shortage of skepticism. Don’t girls face enough challenges in life that parents can’t do anything to prevent? What’s the harm in making their lives a little less difficult by dropping off forgotten homework or lunch on our way to work? Won’t not failing help them become self-confident and capable?

In fact, no. Self-confidence blooms, Gruver said, when a girl screws up and figures out for herself what to do next.

“She learns confidence that she can rely on her inner resources to cope and move forward,” Gruver said, “as well as acceptance that she’s not always going to be in control of everything that happens, and resilience that she can go forward and say, ‘I’m still here.’ ”

Primed for perfection

This is certainly true for our sons, too. But research by educators including Rachel Simmons, founder of the California-based nonprofit Girls Leadership, has found that when girls make mistakes, they’re much more likely to blame the setback on their lack of talent or ability.

Boys seldom make that connection.

Girls also are primed for perfectionism, which Gruver said “is a hollow power that shatters easily with the smallest mistake or judgment from someone else.”

She has personal experience there. “I was a kid who really didn’t fail,” she said. “School happened to be easy for me. I learned to not work too hard. If I had to struggle, I figured that I shouldn’t try it.”

She can’t blame her parents. “That was not the message my parents gave me,” she said. “They weren’t examining all the time, and they certainly never looked at my homework.”

What a difference a generation makes. It’s a rare parent today who isn’t examining or helping with homework. Or delivering it to school when it’s forgotten on the kitchen table.

Love makes us do it, of course.

“There’s nothing more painful than my kids being in a big mess,” said Gruver, author of “How to Say It to Girls: Communicating With Your Growing Daughter.”

“It doesn’t matter what the quandary is. It’s just so painful to experience that as a parent.”

That means we grown-ups have our homework cut out for us if we want to help our daughters succeed. Author Lahey is confident that we can retrain our brains, no matter how old our daughters are.

“Parents of older kids come to me sometimes in tears,” said Lahey, who also teaches high school English. “They’re worried that it’s too late and they don’t know how to turn it around.

“But, it’s as simple as changing your perspective from short-term goals to a long-term goal of developing competent kids who can make mistakes and learn from them.”

Kids as young as kindergartners are well-primed to practice age-appropriate versions of these skills, too, she said.

How to give autonomy

First, Lahey said, you have to be on same page with your spouse, former spouse or significant other.

Next, you need to let teachers know that you won’t be responding as you have previously.

“You can tell the teacher, ‘Look, I’m trying to give my kid more authority, so you might need to e-mail me or call me if things spiral out of control, because I won’t be checking.’ ”

Next is the toughest job. You need to go to your child and say, “I’ve screwed up. I’ve done this wrong. All that need you have for autonomy? I’m going to start giving that to you. Here are the expectations and here are the consequences.”

Expectations might look like this: “Homework will get done. It will get done well. It will go into your backpack. And it will come out of your backpack.”

And the consequences: “If that doesn’t happen, you must talk to your teacher.”

The final step, Lahey said is to “cross your fingers.”

She’s only half kidding. Things typically get messy for a few weeks as everybody adjusts. Then most kids meet the independence challenge in ways that will warm a modern parent’s heart.

Gruver, who lives in the Bay Area, recalls a story from her own early motherhood. One of her twin daughters, a ballet dancer, experienced a serious ankle injury. Gruver and her husband, Joe, leapt in to help with suggestions and strategies for mitigating physical pain, as well as the emotional pain of a dream deferred.

“Then she said to us, ‘I don’t want you to solve this problem. I just want you to listen to me.’ It really shined a bright light for me.”