Mbh 1.120.7a

“Vaisampayana continued, ‘Hearing these words of the ascetics, Pandu, remembering the loss of his procreative powers owing to the curse of the deer, began to reflect deeply. And calling his wedded wife the excellent Kunti, unto him, he told her in private, ‘Strive thou to raise offspring at this time of distress. The wise expounders of the eternal religion declare that a son, O Kunti, is the cause of virtuous fame in the three worlds. It is said that sacrifices, charitable gifts, ascetic penances, and vows observed most carefully, do not confer religious merit on a sonless man. O thou of sweet smiles, knowing all this, I am certain that as I am sonless, I shall not obtain regions of true felicity. O timid one, wretch that I was and addicted to cruel deeds, as a consequence of the polluted life I led, my power of procreation hath been destroyed by the curse of the deer. The religious institutes mention six kinds of sons that are heirs and kinsmen, and six other kinds that are not heirs but kinsmen. I shall speak of them presently. O Pritha, listen to me. They are: 1st, the son begotten by one’s own self upon his wedded wife; 2nd, the son begotten upon one’s wife by an accomplished person from motives of kindness; 3rd, the son begotten upon one’s wife by a person for pecuniary consideration; 4th, the son begotten upon the wife after the husband’s death; 5th, the maiden-born son; 6th, the son born of an unchaste wife; 7th, the son given; 8th, the son bought for a consideration; 9th, the son self-given; 10th, the son received with a pregnant bride; 11th, the brother’s son; and 12th, the son begotten upon a wife of lower caste. On failure of offspring of a prior class, the mother should desire to have offspring of the next class. In times of distress, men solicit offspring from accomplished younger brothers.