“Depression is the flaw in love,” wrote Andrew Solomon in The Noonday Demon, his exploration of the disease that won the National Book Award in 2001. “To be creatures who love, we must be creatures who can despair at what we lose.” Depression was a scourge he had experienced personally, and the book he produced was intimate yet clinical: Solomon claims that he can veer into self-pity, but it’s not a thing he indulges in on the page. Far From the Tree, the book he has spent the last decade working on,addresses another vast subject, one that isn’t discussed as often as the dark caul of depression. This is a book about families in which a child is flawed—at least in the eyes of much of the world. In it, Solomon expounds on what has turned out to be his great and enduring theme: love and its costs.

In a gargantuan volume that weaves together personal histories (he interviewed more than 300 families), cultural and historical background, and scientific research, Solomon, a journalist and lecturer in psychiatry at Cornell University, describes the steep challenges parents face when they raise children who are not like themselves. He includes chapters on families with children who are deaf, autistic, schizophrenic, severely disabled, transgendered, categorized as dwarfs, diagnosed with Down syndrome, classed as criminals, and conceived as the result of rape. He even has a chapter on prodigies—focusing on musicians—that demonstrates the gulf that being extraordinarily gifted can create between child and parent. While the focus remains on the families he interviewed, Solomon frames his book with two autobiographical chapters. In the first, he describes the alienation he felt growing up with the “horizontal identity” (that is, an identity his mother and father did not share) of a gay man. The final chapter recounts the decision he and his husband made, during the writing of Far From the Tree, to raise from birth a child that was biologically Solomon’s own. (The biological mother was a surrogate.)

The gift Solomon gives readers is insight into situations that many with “normal” families (a term he ceaselessly interrogates) don’t think they could imagine, much less manage. The gift Solomon gives his subjects is sympathy without pity. Solomon encounters not just acceptance but often celebration among the parents of these kids—and an attachment so fierce that it defines for him the universal parent-child bond. In support of that bond, parents of children with extraordinary needs, health issues, or abilities outside the realm of their own experience go to extraordinary lengths. They become researchers, teachers, activists, nurses, coaches, parole officers, and linguists. They move across the country so their children can go to a better school. They spend every cent they have on treatments they can’t afford. They learn sign language. They commit to having their children with them for life, or, equally difficult, to placing them in a home where they can receive the care they need.

Along the way, many parents are surprised at the strength and resourcefulness they discover in themselves. Timid personalities are transformed into “won’t take no for an answer” advocates. Nancy Corgi, the mother of two children with autism, told Solomon, “My entire personality has changed. I’m quick to pick a fight; I’m argumentative. You don’t cross me. I have to do what I have to do, and I’m going to get what I want. I never was like this at all.” Several parents who cared for a child with disabilities and were later diagnosed with cancer or another serious disease told Solomon that their child had instilled in them the fortitude to face their own treatment or even death.

But Solomon does not sugarcoat the cost of raising a child with a horizontal identity. Some couples’ relationships, he found, are strengthened by the challenge. A number of his subjects’ marriages, however, weren’t able to endure the strain, even when both parents remained devoted to their child. Perhaps most difficult of all is the lot of parents whose children don’t appear to absorb or return the love they give. Some kids with autism or multiple severe disability can appear emotionally affectless. People who develop schizophrenia can grow openly hostile and even violent toward family members. As Solomon puts it, “Emotion is not gratis. To love a child who does not evidently mirror your love exacts a more terrible price than other love.”

The stories Solomon tells and the history he recounts illustrate how far scientific understanding and social acceptance of many disabilities and differences have come. School programs and education centers tailored to the needs of autistic learners have been founded, and there are support and advocacy groups for parents as well as autistic people that did not exist until relatively recently. Only a few decades ago, parents who gave birth to babies with Down syndrome were advised in the hospital to have their children immediately institutionalized, or were told that their “ ‘mongoloid’ would never learn to speak, think, walk, or talk.” People with Down syndrome in the public eye, including Jason Kingsley, who in the 1980s was a regular guest on Sesame Street, for which his mother was a writer, and Lauren Potter, a star on the current TV series Glee, have changed social attitudes toward Down syndrome.

But there is still a long way to go. A heartbreaking chapter on transgendered kids tells stories of utter acceptance at the same time that it documents instances of horrific bigotry. Anne O’Hara found that she and her children could no longer live in the Southern community where she grew up when her transgendered adopted son transitioned to a female identity and started going by “Kelly.” When they began receiving threats that Kelly would be killed or mutilated, O’Hara and her children moved out of state.

The subjects of Solomon’s book are, of course, those who agreed to talk to him, and as he acknowledges, they are the parents whose approach to rearing a child who is far from the tree is likely to have been positive and accepting. Many are also well to do, a circumstance that is perhaps in part a function of Solomon’s social circle. (He is independently wealthy.) This means they can afford to go to extraordinary financial lengths, even though, as Solomon found, having money is not necessarily crucial to achieving a better outcome. Icilda Brown, a black woman living in the Bronx who worked as a housecleaner to support her five children, one of whom has learned to live with autism, now speaks to other parents of autistic kids. “I’ll say, ‘You see my son now. And now see your kid’s running and not talking. That was him. If you give up, your child doesn’t have a chance. I looked back, and I said to the Lord, ‘Oh, thank you for bringing me from such a long ways.’ ” Solomon remarks that Brown “seemed more at peace with her son’s condition than almost any other mother I met.”

There’s a reason Far From the Tree is more than 900 pages long—and that the version Solomon originally sent his publisher was twice that length. The stories he tells and the complex moral and philosophical questions he explores take time and space to tease out, and often he stands aside and lets his subjects tell the stories themselves. A major theme of the book is that what is best for one may not be best for all. Solomon mostly leaves it to individuals, both his readers and his subjects, to decide how and where to draw those lines. At one point, he describes a woman who chose to give up her child with multiple severe disability to foster care, commenting, “I am enough of a creature of my times to admire most the parents who kept their children and made brave sacrifices for them. I nonetheless esteem Julia Hollander for being honest with herself, and for making what all those other families did look like a choice.” There are a few times when he is direct about the need to intercede on behalf of a child. After a two-page catalog of cases in which parents have murdered or attempted to kill their autistic children, some out of desperation and others out of a conviction that doing so is altruistic, Solomon balks at the suggestion that there are cases in which mercy killing is justified: “Courtroom leniency sends a message to the society at large, to other parents, and to people with autism that autistic lives are less valuable than other lives.”

Many of the parents he interviewed wrestle with the fact that their children may experience pain and distress as the price of their very existence. Was it right to bring them into the world? Given what they know now, would these parents do it again? Those questions are particularly pointed in the case of a disability such as Down syndrome, for which increasingly sophisticated prenatal tests are available. Once they have children with disabilities, the question these parents face is whether they should wish for a cure for a son or daughter whom they’ve come to accept and love on the child’s own terms—or, barring a cure, what interventions are merited: cochlear implants for the deaf? limb lengthening for dwarfs? hormone treatment for transgendered children?

Not every parent, of course, will choose to bear and raise a child with differences. Many women abort fetuses diagnosed in the womb with a disability. Others carry the pregnancy to full term and give the child up to foster care or adoption. But many of the mothers and fathers Solomon interviewed can’t imagine choosing those options—or are glad they didn’t have them at the moment of decision. “Most of us believe that our children are the children we had to have; we could have had no others,” Solomon concludes. “They will never seem to us to be happenstance; we love them because they are our destiny. Even when they are flawed, do wrong, hurt us, die—even then, they are part of the rightness by which we measure life itself, and they bring us to life as profoundly as we do them.”

Unlike many of the parents in Solomon’s book, Tom and Sue Klebold didn’t know from the time of their son Dylan’s birth about the “identity”—that of a homicidal and suicidal criminal—that would eventually separate them from him forever. Dylan Klebold was one of the two young men who shot 13 people to death at Columbine High School in 1999. But like the other parents Solomon interviewed, the Klebolds have grappled with the complex emotional and moral calculus of having brought their child into the world.

Solomon ends his chapter on juvenile criminals with Sue Klebold’s words: “When it first happened, I used to wish that I had never had children, that I had never married. If Tom and I hadn’t crossed paths at Ohio State, Dylan wouldn’t have existed and this terrible thing wouldn’t have happened. But over time, I’ve come to feel that, for myself, I am glad I had kids and glad I had the kids I did, because the love for them—even at the price of this pain—has been the single greatest joy of my life. When I say that, I am speaking of my own pain, and not of the pain of other people. But I accept my own pain; life is full of suffering, and this is mine. I know it would have been better for the world if Dylan had never been born. But I believe it would not have been better for me.”