So the Bhagavad Gita is the part of the Mahabharata where you have Krishna talking to Arjuna and reassuring him about his role in life. And this is what Krishna tells Arjuna. A Brahmin's virtues, born of his nature, are serenity, self-control, austerity, purity, tolerance, honesty, learning, and to know the truth of things which be. A Kshatriya's pride, born of his nature, lives in valor, exuberance, determination, resourcefulness, bravery in battle, and generosity and noble demeanor as a lord of men. A Vaishya's task, born with his nature, is to till the ground, tend cattle, venture trade. A Shudra's state, suiting his nature, is service, arguably in service, to the other three classes. Now once again, it doesn't make strict reference to you are born a Brahmin.