Sun Wukong
There is nothing in Journey to the West, but you can know the answer to this question from other ancient books. In the map of this mountain, such a story is recorded. Dayu is not an ordinary person. He is the child of Nu Wa. According to legend, Dayu is a stone in a mountain stream. One day, Nu Wa was drinking water by the river. She found the stone round and beautiful, so she swallowed it.
Later, Nu Wa gave birth to a child, and this child was Dayu. Later, Xia Qi, Dayu's child, also emerged from the body of Tu Shanshi, his petrified mother. Therefore, it can be seen that the Dayu family has the ability to breed life in stones. From this, it can be understood that the Monkey King's father is probably the ancient Dayu.
Another very strong evidence is that the Monkey King has been lacking a weapon that can be used since he claimed to be the Emperor. Then the Monkey King went to the East China Sea Dragon King for help. The East China Sea Dragon King didn't dare to neglect the Monkey King, so he took out all his weapons at home. But the Monkey King didn't like it until the East China Sea Dragon King had no choice but to recommend the golden hoop to the Monkey King. I didn't expect the great staff to listen to the Monkey King and be flexible in the Monkey King's hands. Why is this happening? Because the Monkey King is a child of Dayu, and the golden hoop is a tool used by Dayu to measure the depth of the sea. The Monkey King naturally knew everything about his father.