ŚB 3.5.9

Every living being is under the plan of his natural inclinations in terms of the modes of material nature. His work is manifested in terms of the nature of the three modes, his form and bodily features are designed according to his work, and his name is designated according to his bodily features. For example, the higher classes of men are white (śukla), and the lower classes of men are black. This division of white and black is in terms of one’s white and black duties of life. Pious acts lead one to take birth in a good and highly placed family, to become rich, to become learned and to acquire beautiful bodily features. Impious acts lead one to become poor by parentage, to be always in want, to become a fool or illiterate and to acquire ugly bodily features. Vidura requested Maitreya to explain these differences between all the living creatures made by Nārāyaṇa, the Supreme Personality of Godhead.