So Isaac is old and blind, and he tells his son Esau to hunt him down some game to eat. So Esau goes off hunting.
Meanwhile, Rebecca, Jacob’s mom, has overheard her husband. Hey, Jacob, she says, take this tasty food and bring it to your father and pretend you’re Esau. But Jacob has doubts. “Esau my brother is a hairy man and I am a smooth man,” he says. No problem. She clothes Jacob’s hands and neck with goatskin.
Now Jacob is getting into this. He goes into his father’s tent and his dad asks “Which one are you, my son?” And Jacob says “Esau.” Then he feels Jacob’s “hairy” hands and he says “Are you he, my son Esau?” You can see that, just because Isaac is old and blind, he’s no dummy.
The reason Isaac is convinced that this is Esau is that Jacob is wearing Esau’s clothes, which “smell of a field that God has blessed.”
So Jacob gets the blessing and, later on, gets his name changed to Israel, which is why we’re all called Israelites.