One of the black mark that Indian or Hindu society is that of the caste system . Th MANU SMRUTI , as I was told has also mentioned the Cast system and the inheritance . If a higher class man is married to same class woman, she gets higher percentage of his property than the lower cast women who is also married to the same man. So we as society have decided that the cast system is based on birth . In Bhagwat Geeta also there is mention of cast system. One of the shloka states that 'even Shudra and women can achieve me ---"So we have cast system and that was based on the birth and not on QUALITIES that one has .
The cast system is based on or is supposed to be based on what qualities one has and should not be based on which family one is born. This is related to 3 Gunas. The 4 casts are BRHMIN, KSHATRIYA,VAISHY AND SHUDRA. The Brahmin is supposed to be higher cast and Shudra is suppose to be lower cast. But in reality the basis for this classification is , on predominance of 3 Gunas. When the SATWIC Guna is dominant and the Rajasic is less prominent and Tamasic is minimal then the person is BRAHMIN. The the Brahmin are suppose to be teaches and priests and may be in professions which help people . They are not Fighters or soldiers and certainly not business people.
When a person has prominence of Rajasic Guna and some of Satwic Guna and very little Tamasic Guna, then that person is kshatriya . These are soldiers or fighters . They do have Tamasic Guna proportion more than seen in Brahmins but Rajasic is much more and Satwic is less than seen in Brahmin.
When the person has predominant Guna of Rajasic and less of Satwic and some of Tamasic , then they are VAISHYA or businessman . The Satwic is less than seen in Kshatriya and certainly much less than Brahmin , and Tamsic is much more than seen in Kshatriya.
The Shudra cast is suppose to be determined by predominance of Tamasic Guna . They do have some Rajasic and some Sattvic , but much less than Kshatriya and Vaishya casts.
The interesting part is that in reincarnation, one is reborn to fulfill his or her DESIRES and so one who is addicted to alcohol is likely to be born in family where alcohol is easily available and consumed . So the person born in a family of one cast is more likely to have same Guna proportion as mentioned above , though there are exceptions. So though the cast should not be determined by the birth family cast, many may have same attitude and so they are menially and by birth belong to the same cast.
Again I FEEL THAT CAST SYSTEM IS BLEMISH ON HINDU SOCIETY AND BIRTH SHOULD NEVER DETREMINE THE CAST, BUT THE QUALITIES SHOULD DECIDE IT