Counting down the days until the wedding, Alice and François decide to organize a great meeting of their families, who come from very different backgrounds. And by the way, they encourage parents and future in-laws to take DNA tests together. Their result will leave everyone stunned. Because what could be worse for a conservative bourgeois than to find out that he is not 100% French? Or for the proud car salesman on the Seine that he has suspiciously German roots? And this is only the beginning of family and genetic problems.