26
Śrīmad-Bhāgavatam
[Canto 9, Ch. 1]
māsaṁ pumān sa bhavitā  
 māsaṁ strī tava gotrajaḥ  
 itthaṁ vyavasthayā kāmaṁ  
 sudyumno 'vatu medinīm
tuṣṭaḥ —being pleased;  tasmai —unto Vasiṣṭha;  saḥ —he (Lord Śiva);  bhagavān —the most powerful;  ṛṣaye —unto the great sage;  priyam āvahan —just to please him;  svām ca —his own;  vācam —word;  ṛtām —true;  kurvan —and keeping;  idam —this;  āha —said;  viśāmpate —O King Parikṣit;  māsam —one month;  pumān —male;  saḥ —Sudyumna;  bhavitā —will become;  māsam —another month;  strī —female;  tava —your;  gotra-jaḥ —disciple born in your disciplic succession;  ittham —in this way;  vyavasthayā —by settlement;  kāmam —according to desire;  sudyumnaḥ —King Sudyumna;  avatu —may rule;  medinīm —the world.
TRANSLATION
O King Parikṣit, Lord Śiva was pleased with Vasiṣṭha. Therefore, to satisfy him and to keep his own word to Pārvatī, Lord Śiva said to that saintly person, “Your disciple Sudyumna may remain a male for one month and a female for the next. In this way he may rule the world as he likes.”
PURPORT
The word  gotrajaḥ  is significant in this connection.  Brāhmaṇas  generally act as spiritual masters of two dynasties. One is their disciplic succession, and the other is the dynasty born of their semen. Both descendants belong to the same  gotra , or dynasty. In the Vedic system we sometimes find that both  brāhmaṇas  and  kṣatriyas  and even  vaiśyas  come in the disciplic succession of the same  ṛṣis . Because the  gotra  and dynasty are one, there is no difference between the disciples and the family born of the semen. The same system still prevails in Indian society, especially in regard to marriage, for which the  gotra  is calculated. Here the word  gotrajaḥ  refers to those born in the same dynasty, whether they be disciples or members of the family.