The Vishnu Purana has a different tale about the descendents of Uttanapada who was one of Manu's sons.
Uttanapada was married to Suniti. They were quite unhappy because, although they were getting quite old, the queen had been unable to produce an heir to the crown. Since the continuance of the line was imperative, the queen insisted that her husband take a second wife. The king initially opposed the idea but finally relented. He married Suruchi, his second queen, who soon bore him a son, Uttam.
As it turned out, Suniti, the first queen, also became pregnant after some time and gave birth to a son who was named Dhruv. This did not please the second queen who clearly wanted her son to become the crown prince. She was quite jealous of the newborn and his mother and did everything necessary to win the king's favor for herself and her son. Consequently, the king spent increasingly less time with Suniti and Dhruv. So Suniti was forced to live outside the royal palace with her son Dhruv, while Suruchi and her son Uttam enjoyed all the luxuries in the palace. It is no coincidence that Suruchi means "the desire to enjoy' whereas Suniti means "that which is correct".
Once Uttam was sitting on the king's lap when Dhruv arrived there and wanted to sit on his father's lap. But for the fear of Suruchi the king did not take Dhruv in his lap. Suruchi came just then and she ridiculed Dhruv. She said, "Though you are also a son of the king, you have no right to sit on the throne because you are not born to me. You are the son of queen Suniti who is neglected by the King. If you wish to have the throne, you must worship Lord Narayana (another name of Vishnu), and take birth through me and then wait for your chance to sit on the king's lap."
Hurt by his stepmother's harsh words, Dhruv vowed to achieve a place significantly higher than his father's lap. When Suniti heard about the incident, she felt very sorry. Still, with patience she consoled her son Dhruv. "O my son, don't wish ill for the others. Those who cause sorrow for others, have to face the outcome themselves one day. Your stepmother is right. You have been born to me. Even then, if you wish to be enthroned like the prince Uttam, give up your jealousy and start worshipping Lord Narayana. Before you go, ask for the blessings of Suruchi."