Ashtavakra is a sage who got this name because his physical body was having eight bends since his birth. Ashtavakra is the author of the text Ashtavakra Gita also known as Ashtavakra Saṃhita
His maternal grandfather was the Vedic sage Aruni (आरुणि) or Udalaka (उद्दालक). The father of Ashtavakra was Rishi Kahoda (कहोड़) and his mother was Sujata, who indeed was sister of Shevaketu (श्वेतकेतु) and daughter of sage Aruni.
Why was Ashtavakra has eight bends in his body ?
This story is mentioned in Mahabharata Vana Parva.
Rishi Kahoda was one of the student of Aruni, along with his daughter Sujata. Aruni’s daughter married Kahoda. She got pregnant, and during her pregnancy, the developing baby heard and learned the Vedas in the womb itself.
Ashtavakra was in womb when he heard his father reciting the Vedas, but his pronunciation was not correct, so Ashtavakra spoke from the womb and asked his father to correct the eight mistakes that he was doing while reciting the mantras. Ashtavakra’s father got angry and cursed him to be born with eight deformities, hence the name ‘Ashtavakra’ ( यस्मात्कुक्षौ वर्तमानो ब्रवीषि तस्माद्वक्रो भवितास्यष्टकृत्वः)
Ashtavakra’s father rishi Kahoda, once went to Janaka, the king of Videha. There he was defeated in debates by another scholar named as Bandi (बंदी), and as a result of his defeat he was immersed in water. When Ashtavakra grew up, he learned about his father.
Ashtavakra decided to go to the palace of king Janaka, and have the debates with Bandi. When Ashtavakra reached Janaka’s palace , he was stopped from entering the palace as only learned Brahmanas and Kings were allowed to enter, and he was just in his tenth year. With his knowledge he proved to Janaka that he is fit for the debate with Bandi and was allowed to enter in the palace.
There he challenged Bandi and after a heated debate, he defeated Bandi. He than asked the king Janaka to drown Bandi in water, as the Bandi use to do with the loser of debates.
Bandi then revealed that he is the son of Varun, and explained that the reason he drowned those Brahmins to take part in a ritual that his father is performing from twelve years and that ritual needed a large number of Brahmins. They all are alive and he can call them if needed. Finally Bandi calls rishi Kahoda and make him present before the Ashtavakra.
Hearing the Ashtavakra has defeated Bandi in debate, his father was very impressed from his son, and while going back home asked him to take a dip in the river ‘Samanga’. As Ashtavakra came out of the river, all of his deformities were cured.