Why would that be the stretch, of anything else? It's well documented that there are many species of parasites, and even fungi, that infect a host and drive it to be consumed or otherwise killed for a purpose specific to the parasite.

Cordyceps are a species of fungi that infect various insects, take over their body, and direct them to climb up high, before the fungus uses the host as feed to grow out and distribute spores. Look up Zombie Ants.

There's a worm that spreads its eggs via bird droppings. Snails that eat or cross over the droppings take the eggs into their bodies, whereupon the infants reenact the cordyceps, except of sprouting miniature towers out of the back of the snail's heads, they direct the snail into open spaces then travel into the snail's eyestalks and cause them to bulge and pulsate to mimic a caterpillar to attract birds. The bird eats the snail, the worm lay its eggs in the bird's digestive tract, and the bird defecates and spreads the eggs around.

In the case of the rats that are directed to be eaten by cats, this last case is the most likely motive. The parasite gets in the rat, drives it to be eaten, then uses the predator's body and feces to distribute its eggs, so that the cycle can begin anew.

In the case of what the OP is presenting, there's already an existing case of parasites driving homosexuality in nature. There's a species of parasite that infect male crabs, cause certain physiological changes and the drive to act like a female, so as to attract other males to mate with the host, so that the parasite can spread.