Does Kino choose his destiny or his fate, and how does this fate affect his life in The Pearl?

It would seem that Kino does choose his fate. For, after the pearl dealers offer him far less than the Pearl of the World is worth, he refuses when Juana urges him to crush the pearl between two stones and cast it from his mind. 

When Kino refuses to destroy the pearl, he tells his Juana,

"I will fight this thing. I will win over it. We will have our chance...No one shall take our good fortune from us....I am a man."

This choice changes the lives of Kino and his family as from then on there is a reversal of fortune. On the night after Kino has gone to the pearl dealers, Juana sneaks outside and discovers the great pearl in the brush on the path behind a large rock. Kneeling, Juana ponders whether to take it and throw it into the sea, but as she does so, the moon reappears from behind a cloud, revealing "two dark figures" who are lying on the path just ahead of her. Juana leaps to her feet and discovers Kino over a stranger who is bleeding. Seeing this dead man, Juana knows that "the old life was gone." Kino believes his pearl has been stolen, but Juana returns it to him.

Now, they must flee their home. So, they head to the Sierra de la Giganta, hoping to go to Lorento, a town to the north, but trackers eventually find their trail. Kino and his family hide in a cave; in the night, Kino ventures out and sees a match flare down on the beach. Three men are there; two are asleep while one watches with a rifle. Kino sneaks down the rocks to try to grab the rifle away from the one holding it. But, as fate would have it, his baby cries out just as Kino is in midleap, and the man shoots because he thinks he hears a coyote. Coyotito (whose name is ironically similar) is shot in the head by this random bullet of fate. Kino lands on the man too late as he hears the "cry of death" from Juana.

Defeated by fate, Kino and Juana return to their home; they walk to the beach, and Kino pulls the pearl from his clothes. As he looks down at the pearl, it seems malignant and grey and distorted because in it he sees his dead baby and the tragedy of their lives. Drawing back his arm, he flings the pearl as far as he can into the sea.