Well, Joseph is one of Jacob's sons, so it is important not to confuse the two.
When you think about it, it wasn't fair to begin with. Esau had the birth right just because he was older. Jacob used his own ability (being clever) to get the birthright from Esau, who didn't really even care about it that much.
The point of the story is that Jacob, ancestor of the Israelites, is the underdog, and he uses trickery to gain the underhand. However, he gets a taste of his own medicine from his uncle Laban later on
