For nearly a year, starting when she was 2, Josie begged for a sister. “I will share my toys! I will kiss her! I will feed her!” Imagine how thrilled we were to announce, just before Josie turned 3, that she would be receiving her heart’s desire. And when we brought Maxine home, Josie was elated. She raced around the apartment singing “Happy birthday” and dancing maniacally. She showered the baby with kisses. She held her gently. After a couple of hours, though, she asked, “Where will the baby sleep?” Upon being told, “Here—she’s going to live here,” Josie’s eyes narrowed. Perhaps she thought the crib that had materialized in her room was for the cat.Fortunately, I did not look to the Torah for advice on raising siblings. Sibling relationships in our tradition are a mess, starting with Cain and Abel (result: dead Abel.) It goes on and on: Isaac and Ishmael, Esau and Jacob, Leah and Rachel, Joseph and his brothers. Good times all around.But who can blame our ancestors for being such crappy siblings? For generations, no one in their family modeled healthy familial relationships. Science, not just story, backs up the fact that sibling favoritism can have nasty consequences. A 2009 studyof moms of adult children, published in the Journal of Marriage and Family, found that perceived favoritism hurts both the “favored” and “unfavored.” It’s obvious why the latter would be irked by “Mom always liked you best!” but the former also showed depressive symptoms, even years later as middle-aged adults. Favorites felt guilt as well as the need to cope with negative, distant, resentful siblings.Parents do acknowledge that they’re closer to some kids than others. (But is that really favoritism? You tell me.) In the 2009 study, 70 percent of the moms surveyed named one kid they felt closest to, and 73 percent named a kid with whom she had the most arguments and disagreements. Another study,this one from Current Directions in Psychological Science, found that a third to two thirds of American families evidence parental favoritism. Sometimes this is natural—parents inherently give newborns and kids with illness or disabilities more attention. Sometimes it’s surprising: Parents often feel closer to their same-gender children; first-born children get the most privileges and last-born children get the most affection. Jan Brady was right. It’s tough to be stuck in the middle.However—and this is key—kids seem to feel there’s more parental favoritism than there actually is. In that same study, only 15 percent of children said their moms showed no favoritism at all, but 30 percent of moms said they didn’t have favorites.Do I love one child best? When my own spawn demand an answer to this question, I reply with the excellent words of writer/therapist Amy Bloom: “Love is not a pie.” Love is not a finite thing to be sectioned up and doled out; it’s infinite. My kids are never satisfied by this answer.And I mostly don’t believe I have a favorite child. Mostly. But then I think back to a brutally truthful 2006 essay by Ayelet Waldman in the late, lamented Child magazine. Waldman, with her typical coruscating honesty, wrote that she let her youngest child get away with murder because she couldn’t resist her adorability. Her older kids noticed. “What’s killing them is that they are absolutely sure she’s my favorite. And they’re right—she is. Right now.”Waldman goes on to explain that different kids hold the privileged position of favorite at different times. “You must never favor one child over the other, the rule goes,” she writes. “But the secret, hidden truth is that we often do. Parenting is a passionate enterprise. It’s about love: untempered, unbound love. And anyone who has ever been in love knows that it’s not a judicious, balanced endeavor.”My truth is that I love my kids differently. I am gobsmacked by Josie’s insights. I love talking about books and social justice with her. As a dork and a nerd, I watch with endless admiration the way she navigates the world socially. But I feel fierce protectiveness toward Maxine. She’s the one who squeezes my heart until it hurts. Her cheerfulness and funniness and resilience just slay me. Does that mean I love Maxie more?In the recently released book Freud’s Blind Spot, Elisa Albert, a contributor to Tablet Magazine, collects essays about the pleasures and terrors of siblinghood. The book’s title refers to the fact that Freud gave short shrift to sibs. “Some scholars have lately called for a reassessment of [this] vertical model,” Albert writes. “What about the horizontal model, they ask? What about lateral influence?” (The italics are hers.)Indeed, she finds, “Our siblings are central actors in the drama of our lives: they are our earliest and deepest connections, our poles, our friends, our contemporaries, our cohorts, our first loves and resented rivals … we tend to define ourselves in alliance with and/or in opposition to them.” Of the familiar Erev Shabbat blessing, “May you be like Ephraim and Menashe,” Albert writes: “Recently I learned it’s because Ephraim and Menashe are the only two siblings in the Bible who get along.” Oh.The book is filled with stories of siblings who fight furiously. Sometimes they come to love and understand each other. Sometimes they don’t. Steve Almond writes about how when he was 5, his older brother, Dave, told him their pregnant cat Macacheese (Macacheese!) has just birthed a litter of stillborn kittens because Steve had accidentally dropped her the week before. (Later, knowing that Steve sucks his thumb, Dave secretly rubbed his digits with a raw hot pepper.) Another contributor, Margo Rabb, doesn’t grow close to her sister until after her parents are dead. “We share genes, a history, and the only bits of our parents we have left,” she writes. “And she’s the only person who understands how we can sit beside our parents’ graves on a sunny afternoon, and then go out for sushi and stuff ourselves and still laugh, even now, until we nearly burst.”Apparently stabbing one’s sibling with a pencil is a thing. T. Cooper spikes one into his brother’s thigh. Alyssa, a 6th-grade character in Caldecott-winning poet Joyce Sidman’s incredible This Is Just to Say: Poems of Apology and Forgiveness, writes to her sister Cassie:The Black Spot\n\n\n\nThat black spot on your palm.\nIt never goes away.\nSo long ago\nI stabbed you with a pencil.\nPart of the lead, there,\nstill inside you.\nAnd inside me, too,\nsomething small and black.\nHidden away.\nI don’t know what to call it,\nthe nugget of darkness,\nthat made me stab you.\nIt never goes away.\nBoth marks, still there.\nSmall black\nreminders.In a response poem, Cassie says only:Roses are red\nviolets are blue, \nI’m still really \npissed off at you.So sisterhood is powerful, in both good and bad ways. I’m not sure what I can do not to play favorites. I try to spend solo time with each of them. I try not to play them off against each other. I keep chanting, “Love is not a pie.”I can see that the relationship my daughters have is a million times more intense than the one my brother and I had. My brother and I didn’t have much in common. Growing up, we didn’t have much to say to each other. Josie and Maxie, on the other hand, love and hate each other with fierce devotion. They play Legos together for hours. Josie reads to Maxie. Maxie comes home from school with dozens of drawings of Josie. They bring each other goodie bags from parties. And they fight like rabid animals. And they insist I love the other one more.I can take heart from a recent study showing that people with sisters grow up to be better at coping with setbacks, more highly motivated, more optimistic, and more social than people with only brothers. Researchers theorize that sisters talk a lot (God knows this is true in my house), and open emotional expression is good for one’s mental health. Boys, on the other hand, discourage such verbal sharing.When it comes to raising our progeny, we parents are bound to screw up sometimes. It’s a given. And it’s scant consolation that we’re bound to do better than our biblical forebears. We just have to make sure our kids understand that after we’re gone, they’ll have each other.Today, Maxie’s crib is gone. We have bunkbeds. When they arrived, Maxie cried bitterly because Josie got the top bunk. But Josie has never spent a single night in it. After storytime, she climbs down into Maxie’s bed. I often find them intertwined, like puppies, in their sleep.Marjorie Ingall is a columnist for Tablet Magazine, and author of Mamaleh Knows Best: What Jewish Mothers Do to Raise Successful, Creative, Empathetic, Independent Children.