Sisters Audrey Findlay, 75, and Barbara Rowe, 63, Every workday starts with an 8am call. About an hour later, they headed to work together at Findlay Rowe, the gift shop they opened 12 years ago. (Previously, they had worked at the same health care company for 13 years, Ms. Findlay as general manager and Ms. Luo as payroll manager.)

At 5 or 6 p.m., the sisters come home from get off work—four houses apart. After dinner, they got together for another hour-long walk, easing into what their grown children (they have nine) affectionately called “twin talk.”

“One of us would start a sentence, not end it, and the other was already answering,” Ms Findlay said.

The sisters do have their arguments, as expected from two people who regularly spend most of their time together. But they are committed to staying close and serving each other.

“Our father was an orphan and he had a very strong attachment to the family,” Ms Luo said. “We can have a tight, drawn-out fight and the next day it’s like: ‘Okay, where are we going for dinner?'”

More than 80 percent of Americans grow up with at least one sibling, and studies show that these relationships can have benefits into adulthood. For example, a 2019 study of people in their 60s found that warmth between adult siblings may buffer loneliness and help boost well-being.

While there isn’t much research on how most adults get along with siblings, the 2015 book Adult Sibling Relationships, co-authored by Geoffrey Greif, a professor at the University of Maryland School of Social Work, A book showing data offers some clues. In qualitative interviews with 262 adults, 64% said they considered themselves “good friends” with at least one sibling, and 45% said they considered at least one sibling to be their best friend.

However, Dr. Greif said in interviews that 70 percent said they had ups and downs with their siblings in their lives, and 8 percent said they were never close.

“Siblings, like all family relationships, have a certain level of conflict and ambiguity,” Dr. Greif said—perhaps an obvious statement, but he thinks it’s important for siblings so they don’t Will set the “impossible standard” needed for a strong relationship.

He and other therapists who focus on family relationships believe that it’s possible to strengthen the bond between adult siblings, even if you don’t have (or even desire) the kind of tight bond that Ms. Findlay and Ms. Rowe have. Here are three strategies that can help.

Allow each other to change.

Nicholas Gant, 40, and his sister Gaybrielle LeAnn, 37, were very close as children — according to family lore, Mr. Gant taught his little sister to walk and talk. But during adolescence, they drift apart. Ms LeAnn described her brother as a talented singer who was kind and charismatic; she said this created a “natural magnetic field” around him that sometimes made it difficult for her to find her voice.

Both attended Black Colleges and Universities (HBCUs), an experience they say taught them the importance of building community and helped them “recognize our need for each other,” Mr. Gant said. He and Ms. LeAnn spent their 20s and 30s getting to know not only themselves, but another sibling who especially valued and understood: If Mr. Gantt, a singer, had a show, his sister would be there audience. When Ms. LeAnn celebrated her eighth anniversary of surviving a life-threatening blood clot recently, her brother was there.

“I feel like we’ve really found each other again,” Mr Gant said. “We fell in love again like brother and sister.”

Ms. LeAnn believes that their “ability to grow and love each other as individuals, not just as blood relatives” has helped them become “good friends.”

A willingness to see and embrace sibling growth is important, says Charlotte, N.C.-based therapist Nedra Glover Tawwab, author of No Drama: A Guide to Managing Unhealthy Family Relationships.

“Sometimes they remember a version of you,” Ms Tawwab said. For example, an older sibling may continue to see a younger sibling as a “baby”—even if that baby is 60 years old. “You have to allow people to evolve instead of treating them like you’ve always done,” she said.

To get a better sense of who your sibling is, Miami-based licensed marriage and family therapist Whitney Goodman recommends regularly asking questions like, “What do you like right now?” and “What’s going on in your life? Something you don’t know?”

“I love when people come back to themselves and think: How much have I changed, how much have I grown? How do I want my siblings to see me?” Ms. Goodman said. Then consider, “How can I extend that same grace to them?”

Pay attention to how your parents affect your motivation.

All the therapists interviewed for this story noted that no matter how loving parents are, they can complicate sibling relationships. Dr. Greif says it helps to ask yourself: “Am I ‘triangled’ with my siblings and my mother or father?” Patterns are shaping how you feel about your siblings, even if that wasn’t anyone’s intention?

To avoid this distraction, experts say you can establish a simple ground rule: When you talk to your parents or spend time with them, you don’t talk about your siblings — especially if the conversation takes the form of gossip .

You may also want to find out if parental favoritism is affecting your relationship with your sibling. Survey data shows that 40 percent of Americans feel their parents have a favorite child, and research suggests this can be a barrier to sibling intimacy.

“In research, parental favoritism is one of the biggest influencers on how sibling relationships work, especially in childhood,” Ms Goodman said. “That’s the most limited resource, right? Parental attention. Siblings can definitely carry that into adulthood.”

Ms Goodman said families should not shy away from discussing parental favoritism, although she acknowledged having those conversations was easier said than done. Adult siblings can attend therapy together (with or without parents), even to address something that happened years ago, she says.

Dr Kramer agrees that having this kind of direct conversation can help “repair years of resentment” if people are willing to talk about these kinds of things and be honest about how they feel and be gentle with each other.

Make time to enjoy each other’s company.

Ken LoCicero, 54, and Ricky LoCicero, 58, were best friends and roommates growing up. As adults, they found a grueling way to spend time together: They ran 50 marathons together in all 50 states, a pursuit that took more than 20 years.

This could be an extreme example of making time for each other. But, Ms. Goodman said, siblings sometimes overlook the fact that their relationship requires attention and care just like any other. “We often expect family relationships to thrive just because someone is related to us, but that’s not the case,” she said.

Siblings should find ways to have fun together, said Laurie Kramer, a professor of applied psychology at Northeastern University who runs a program that teaches younger siblings strategies for getting along. “It’s really hard when all of your interactions are about problems that one of you is having,” or when you’re arguing about who will take care of your parents’ needs, she says. “Find moments when you can really enjoy each other.”

Sometimes, pulling out old photos and taking a few minutes to recall them is enough, adds Dr. Kramer.

The LoCicero brothers enjoy game days and how they can often bring their wives and kids for a weekend. But they also love the time they spend training and planning together. Sometimes they run silently. Other times, they talk about work, marriage and children. (The LoCicero family also has a sister who was good friends and a brother who died of pancreatic cancer 15 years ago, a painful loss that has brought them closer.)

Even with their 50-marathon quest, the brothers still talk on the phone or see each other every few days and live just seven miles apart. “I know that Kenny is always available and willing to listen,” Ricky said. He believed nothing could change that connection.

“There’s nothing about Ricky that I don’t want to say out loud,” Ken echoed. Knowing how committed his brother was to their relationship and feeling they could be open and vulnerable with each other was “a gift,” he said.