Others tell a different story about the monkeys:
Gautama left his wife Ahalya and their daughter Anjana alone in the ashram.
Disguised as Gautama, the storm-god Indra slept with Ahalya, and she conceived a son: Vali.
The sun-god Surya did likewise, and Ahalya conceived another son: Sugriva.
Anjana was jealous of her brothers. "They aren't your sons!" she told Gautama.
Enraged, Gautama cursed the boys, turning them into monkeys.
Ahalya then cursed Anjana to stand on one foot atop Mount Kailasha. "Let the wind feed you!"
The wind-god Vayu made love to Anjana there, and she conceived a son: Hanuman.
Inspired by: Sita: An Illustrated Retelling of the Ramayana by Devdutt Pattanaik
Notes: This story is on p. 44 of the book. The legend of the three children of Ahalya appears in south Indian legends and also in the Thai Ramakien and other southeast Asian Ramayana traditions. I have written a longer version of this story: The Birth of Hanuman.
This shows Indra and Surya seeing Riksharaj, not Ahalya: