Hinduism/Sanatan Dharma does talk about Castes, but it was never meant to be hereditary. Sage Vishwamitra who brought down the Gayatri mantra was never a brahmana initially, nor was Valmiki or Veda Vyasa (the compiler of the Vedas !). People had to qualify to become a Brahmana and ofcourse it helped being born in a Brahmana family. Unless a person has the qualities of peacefulness, austerity, determination and firm faith in the Supreme Lord he can't become a Brahman even if he is born in a Brahmana Family. The caste system becomes discriminatory only when you make the system hereditory. Otherwise such a division of society into the intellectual class (brahmanas), warrior class(Kshatriyas), Business class (Vaishyas) and Labourer class (shudras) is natural
