Vasudeva

According to Hindu scripture, Vasudeva (Devanagari , IAST ), also called Ānakadundubhii ("Drum", after the sound of drums heard at the time of his birth), is the father of the Hindu deities Krishna (Vāsudeva, i.e. "son of Vasudeva"), Balarama and Subhadra. He was king of the Vrishnis. He was the son of king Shurasena. Moreover, Vasudeva was not a brother or cousin of Nanda, the foster-father of Krishna. His sister Kunti was married to Pandu. Kunti plays a big role later in the war Mahabharata.    

According to the Harivansa Purana, Vasudeva and Nanda (who took care of Krishna during his early years as a child) were not brothers and Nanda was a Gwala and friend of Vasudeva.

Sage Kashyapa incarnated as Vasudeva
Sage Kashyapa is said to have incarnated as Vasudeva, the father of Krishna due to a curse of the god Brahma. Once, the sage performed a yajna (a Vedic sacrifice) in his hermitage for the welfare of the world. Kashyapa sought the help of the god Varuna for the offerings of milk, ghee etc. Varuna granted the sage a holy cow which will provide the offerings on the condition that the sage returns the same to Varuna after the sacrifice. After completing the sacrifice after several days, Kashyapa was overcome with greed, realizing the miraculous power of the cow, and refused to return the cow arguing that whatever is offered to a Brahmin like Kashyapa should never be sought back, and whoever does that would turn out to be a sinner.

Varuna requested Brahma for intervention. Brahma told the sage to get rid of his greed which is capable of destroying all his virtues, but Kashyapa remained adamant. The enraged Brahma cursed Kashyapa that he would be born on earth again as a cowherd and his two cows Aditi and Surabhi would be his two wives. This was King Vasudeva with his wives Rohiņi and Devaki, and the god Vishnu would be born as his son.

 References 

Category:Hindu mythology
Category:Mahabharata