Documentary about families will make you cry

★★★5 Unrated. 93 minutes.

The documentary “Far From the Tree” takes its title from Andrew Solomon’s best-selling 2012 book in which, with characteristic grace and insight, he interrogated the rejection he felt from his parents when he told them he was gay. Also characteristically, Solomon turned the book into something deeper than a solipsistic wallow, broadening his inquiry to include several other families whose expectations — about children and unconditional love — were upended by real-life experience.

Rather than reproduce Solomon’s book (which, at 800 pages, would have made for an epic slog), filmmaker Rachel Dretzin wisely decided to cast her film primarily with people outside its pages. Readers who enjoyed “Far From the Tree” will instantly recognize Jason, a man with Down syndrome who became a TV superstar in his teens but has settled into a less dazzling but high-performing and contented adulthood with his two similarly abled roommates. And they’ll recognize the elegant, eloquent Solomon, who is a producer of the film and appears on camera with sensitive observations about his own life, conventional notions of happiness and one of the most affecting feel-good scenes of the summer.

But fans of the book will be just as glad to meet Jack, an autistic teenager whose parents are at the end of their rope when they encounter an unexpected breakthrough; Leah and Joe, a photogenic couple who are thriving with dwarfism, and who are contemplating becoming parents; and the Reeses, a family coping with a son who has committed a horrific crime.

In less sensitive hands, suggesting any kind of equivalence between cog- nitive or physical difference and an irrational, reprehensible act could be perceived as fatally problematic. But Dretzin’s aim is to present viewers with multiple versions of one story, which is how parents and children learn to accept one another when things don’t turn out as planned. In the Reeses’ case, the answer is the rueful recognition that love can coexist with a shameful, agonizing truth.

In the case of the other characters, “Far From the Tree” offers bracing examples of people letting go of their preconceptions and projections to celebrate one another for who they are, regardless of labels or limitations.

Of course, getting there can be excruciating, whether it’s Solomon’s recollection of his mother’s reaction to his coming out (“a catastrophe,” as he recalls), to video clips of Jack aggressively lashing out at his mother. Clocking in at just over 1½ hours, the film could have benefited from more detailed material about how the Reeses came to terms with the moral injury of their son’s behavior, both to themselves and to his victim’s family.

But “Far From the Tree” still offers inspiring glimpses of the breakthroughs that can happen when people hang in long enough to come to terms with life’s most sobering realities, be they anatomical or emotional. And it provides welcome ways to reframe notions of normality that are too often conflated with “average.” One of the great gifts of “Far From the Tree” is simple visibility, whereby viewers are given the opportunity to watch people live their lives, share their wisdom and flourish within the loving care of their family and friends.

Fair warning: By the end of “Far From the Tree,” tears will be shed, and for all the best reasons.