The boongiving Brahman, while he created all creatures, himself said that the division of human beings into the four orders as dependant on birth is only for purposes of classification.
एते योनिफला देवि स्थानभागनिदर्शकाः। स्वयं च वरदेनोक्ता ब्रह्मणा सृजता प्रजाः॥