The Borgified Corpse wrote:
werent the Xenomorphs genetically engineered by the Predators?
I doubt it. I think that, once they discovered the Xenomorph species, the Predators began breeding them. There's even an implication that the Alien Queen in Alien vs. Predator
was being pumped full of hormones and that's why the human gestation phase was so much quicker.
The novelization of AVP actually confirms that.