In my opinion this film lets you understand that in your life you can't know what it could happen, and you have to be ready, but sometimes you can't; but it lets you understand how people could change just if they wanted.
In this case, there were two families, an Israelian and an Arabic family, who discovered that their eighteen-year-old sons were exchange at the hospital when they were born.
But it was known that Arabics hated Israelians because Israelian people didn't allow arabic people to be free, infact, although they were almost neighbours, they couldn't believe that they had an Israelian son, especially the older brother couldn't believe it.
At the end of the film, finally each family was happy because they knew their real son, but obviusly Joseph and Yacine, didn't want to change totally family so, step by step, they started to know the family which they really belong to.
The Other Son