What are the names of Matanga rushi's father and mother? Were children of Matanga rushi Brahmins? how did Matanga rushi change his caste? Was Jambavanta a Chandala?
A story of Matanga attaining Brahmanahood is present in Skanda Purana.
His father's name is Sugati. The names of his mother and biological father are not mentioned.
There was an eminent Brahmana named Sugati in Dvapara Yuga. He had control over his sense-organs. He was truthful always and engaged in the study of the Vedas. Matanga was his son who was excessively terrible ever since his childhood.
After realizing that he is a Chandala, Matanga performs intensive penance and attains Brahmanahood. He may be unmarried. Scriptures do not contain any statement related to his marriage and offspring. Finally, he reaches Brahma Loka.
A brief story about Matanga is as follows
As a child Matanga hit a young one of a donkey. The mother-donkey consoled her child telling that Matanga was born of a rape of his mother by a barber and was a Candala. When Matanga heard it, he determined to be a Brahmana by performing penance. Indra dissuaded him and at last sent him to Mahakalavana where, by the sight of this Linga, he became a Brahmana and went to Brahmaloka. Hence the Linga came to be known as Matangesvara.
Although there is a similar story in Mahabharata, some details of the story are different, including the ending. He does not become Brahman in the end.