We've already interfered. Domesticated animals mate more often and have larger litters than their wild ancestors. After neutering, you pet won't know there has been any change, except to be more content and no longer driven to seek a mate. It is the owner's responsibility to have their pets neutered. It is very sad when a female cat has litter after litter, becoming more and more unhealthy with each pregnancy, but having no one who cares enough to stop the cycle.
Neutering makes pets fat and lazy.
Cats, especially males, do put on fat and become more inactive after neutering. However, healthy benefits far outweigh this problem. Weight control can be aided by the owner through discipline regarding feeding and exercise. Roaming tom cats fighting other cats are a neighborhood nuisance. Veterinary bills will be unavoidable with abscesses as a result of fighting.