This kind of commonality, he went on, was something he discovered only while writing. “Each of the conditions I describe is very isolating,” he said. “There aren’t that many dwarfs, there aren’t that many schizophrenics. There aren’t that many families dealing with a criminal kid — not so few but not so many. But if you recognize that there is a lot in common in all these experiences, they imply a world in which not only is your condition not so isolating but the fact of your difference unites you with other people.”

His other great discovery, he added, was joy. He had been prepared to encounter sadness in the families he visited; what surprised him was how much love there was. “This book’s conundrum,” he writes, “is that most of the families described here ended up grateful for experiences they would have done anything to avoid.”

Reviewing “Far From the Tree” in The Times, Dwight Garner said, “This is a book that shoots arrow after arrow into your heart.” But it’s also a frightening and disturbing book. Its chapters are a vivid catalog of all the things that can go wrong in giving birth to and then bring up a child, and also raise difficult ethical questions: whether it’s proper to give cochlear implants to deaf children or to subject dwarfs to painful limb-lengthening surgery, for example.

But Mr. Solomon said that working on the book had emboldened him and his husband, John Habich, to have a child, something he had been ambivalent about before. Their son, George, born to a surrogate mother, is now 3 ½.

“Forewarned is forearmed,” he said. “Some things, on some scale, go wrong in everyone’s life. I think I have perfectionist tendencies, but I know you can’t go into parenthood thinking, ‘I’m going to love my child as long as he’s perfect.’ Rather, it should be, ‘I’m going to love my child whoever he is, and let’s see how he turns out.’ ”

Mr. Solomon — the kind of parent who is apt to give dramatic readings of storybooks — added that being a father has also made him more forgiving of his own parents. “If you’re confronted with a child who’s different, you have to go through this long process of learning to accept and perhaps celebrate the differences in your child,” he said. “The acceptance piece is hard. Part of what I learned from this book is that even for parents who do really well with these issues it’s hard. It was hard for my parents, and that made it harder for me, but I no longer see this as an unacceptable and startling flaw. I just see it as being the way it is.”