“It’s impossible to hate anyone whose story you know,” the nonagenarian mother of a transgendered woman activist tells Andrew Solomon toward the end of this big, big-hearted book. Narrating the stories of hundreds of families in which children and their parents must struggle with identity — whether due to disability or difference of other kinds — Solomon’s project boils down to this: with stories come understanding, empathy, and respect.

Anyone who has children knows that they continually surprise us, beginning even before their birth. Many expect their offspring to resemble themselves, or at least to be amenable to molding; actual babies typically disabuse their parents of that notion. As Solomon says, parenthood involves “a permanent relationship with a stranger” — not that we can’t come to know our children very deeply, but in the end, they are separate, individual, themselves.