Quote Originally Posted by Nova Briar
Do you think it's possible that at least some of the monsters you encounter in the game are descendants of the mutated Cetra?
As I am told quite often, "There is nothing in the game's story to suggest that."
Sephiroth seems convinced that humans are the direct descendants of Cetra who no longer wished to migrate.
(SPOILER)
"The Cetra were an itinerant race. They would migrate in, settle the planet, and move on... and at the end of their harsh, hard journey, they would find the Promised Land and supreme happiness... but those that disliked journey appeared. Those who stopped their migrations, built shelters, and elected to live an easier life. They took that which the Cetra and the planet had made without giving back one whit in return! [points at Cloud] Those are your ancestors."

But in a matter of opinion, a lot of the monsters are ugly enough to be related to Jenova.