A shocking discovery that up-ends both an Israeli and a Palestinian family is at the core of the thoughtful, well-acted French-Israel family drama, “The Other Son.”

As 18-year-old Joseph Silberg (Jules Sitruk), a carefree, curly-haired budding musician, prepares to begin his required military service in Israel, a blood test reveals that he was switched at birth in a Haifa hospital during an emergency evacuation for a bombing. But the real shock is the revelation that Joseph — raised as a Jewish Israeli — is the biological child of a Palestinian couple living in the West Bank. The Palestinian couple is equally taken aback to find they have raised a son with Israeli biological  parents.

The doctor breaks the news to both sets of parents together, in a tense scene where they sit side by side. Both of the fathers, Alon Silberg (Pascal Elbe) and Said (Khalifa Natour) seem to want to drop the subject immediately, but the mothers, Orith (Emmanuelle Devos) and Leila (Areen Omari), tentatively reach out to each other, after leaving the office, with a kind of sorrow.

Joseph’s father Alon is a leader in Israeli security forces and at first simply wants to keep the discovery secret. That proves impossible when Joseph is rejected for military service based on the doctor’s report. Joseph’s French-born physician mother Orith breaks the news to her son with reassurances of their love but Joseph’s first worry is, “Am I still Jewish?” When he poses this question to the rabbi, the answer is disturbing.

The “other son,” Yacine (Mehdi Dehbi), is away at school in Paris, where he lives with his aunt and uncle. Planning to become a doctor, Yacine returns to visit his Palestinian parents in the West Bank after high school graduation, before college starts in fall. His father wants to keep the news from him, fearing the reactions of neighbors, but Yacine overhears his parents arguing about it when Joseph wants the families to meet, and he learns the difficult truth.

This thoughtful yet provocative film is directed Lorraine Levy, from a script she co-wrote with Noam Fitoussi and Nathalie Saugeon. The filmmakers use this unusual but not impossible situation to explore matters of identity, family, faith and the Israeli-Palestinian conflict, with thoughtfulness and humanity.  

Both families are shaken by the news but they react differently. Both teens have younger sisters who immediately bond when they meet. Both mothers struggle with fears of losing their son and worry about feelings of rejection if they each give into curiosity about the other son. Dealing with people outside the family pose special issues and both must grapple with their identity.

Perhaps the most upset at this news is Yacine’s older brother Bilal (Mahmood Shalabi). Bilal resents the wall that runs along his neighborhood, the checkpoints and the restrictions imposed by the Israeli government. Both boys are disturbed to find a new attitude towards them by Israeli security forces, a sudden wariness towards Joseph, despite his father’s official position, and sudden smiles from checkpoint guards for Yacine, and jokes about being “one of them.”

When the families meet, a kind of tentative friendship evolves between the two boys. The film carefully and slowly explores the situation, so that issues come up in a natural sort of way. The two young men and their various family members are presented as fully rounded individuals, avoiding any pat answers or stereotyping.

This worthy film takes a fresh approach to explore difficult issues with care and thoughtfulness, pushing the edges of understanding in just the right places, through these two unique families. With two different families, the outcome could have been different, but these families find it in themselves to give the other the benefit of the doubt, and perhaps a bit more.