The Buddha resolves the dispute between two brahman youths. One held the belief that a brahman was a brahman because of birth, the other that a brahman was a brahman because of deeds. In many examples the Buddha shows that one is a brahman because of deeds.
Read the Sutta
This sutta is hard to swallow as an authentic utterance of the Buddha. The point is within the scope of the Dhamma, the argument over all is reasonable, but the details are carelessly put and subject the whole argument to rebuttal. Gotama is not a careless speaker. For example it is said here that there is no difference in color. (Color is also 'cast', but here it uses as an example the differences in color between animals.) But we see there are differences in color. We can see differences in some of the other characteristics which this sutta claims are not different. The human being can be bread to bring out differences like any other animal and that has happened over time. The idea is that any differences in physical characteristics between human beings resulting from birth are superficial in the sense that they are not taken into consideration in the determination of nobility of character.
Personally I would put this sutta to one side as being doubtful. It seems probable that it was an elaborated version of some real discussion, but the story-teller got carried away with himself.