By Mike Miller
April 25, 2018 01:41 PM

After taking readers inside the lives of hundreds of families of children battling differences and disabilities with his 2012 bestselling book Far from the Tree: Parents, Children and the Search for Identity, author Andrew Solomon is narrowing the scope of his work for a feature film adaptation.

In the upcoming documentary Far from the Tree, Solomon focuses on six families accommodating children with a wide variety of physical, mental and social differences and disabilities. Watch the first trailer for the film — exclusive to PEOPLE — above.

“Seeing one’s most cherished work translated into another medium can be exhilarating like almost nothing else,” the author tells PEOPLE. “I was approached by more than twenty filmmakers after the book Far from the Tree came out, and I know I picked the right one.”

The IFC Films/Sundance Selects

He explained, “While the book has three hundred families and the movie has six, those six convey what I intended and discovered and so much more: about love; about the complexity of parenting; about identity; about grace; about faith; about optimism; about how people come to be grateful for lives they would have done anything to avoid.”

In the trailer, Solomon explains that growing up gay in a family that didn’t always accept him helped inspire the book. Now, he hopes that the upcoming documentary will provide audiences with an even better understanding of what these extraordinary families face every day.

Andrew Solomon.

“There is a thrilling, unparalleled intimacy to film, and director Rachel Dretzin has made a film that is generous and wise,” Solomon says. “I believe it will reach both readers of the book and a far broader audience, and tell them how our differences can unite us and how fortunate we can be in whatever lives we are given.”

The author also cited today’s political climate for making the film especially pertinent. “In a moment when the value of diversity is being questioned on a national stage, this is a film full of beautiful truths and enduring hope.”

Far from the Tree opens in theaters July 20.