There are good reasons to neuter a male cat during the first six months or so of his life. In addition to population control, neutering eliminates or at least reduces the occurrence of some undesirable sex-related behaviors.
Source: Catster, August 2017.
Nicholas Dodman, BVMS, notes that about 10 percent of neutered cats will continue to display unwanted behaviors. “Owners should know that, in some cats, neutering does not completely turn off the sexual lights,” he says. “Instead, the procedure sort of turns the dimmer switch way down, but there’s still enough of the male behavioral instinct remaining to be problematic.”