"Are there people feeding them, are they stealing the food, is it bad hygiene in restaurants?" Bradshaw said.
Reduce the available food, and the feral-cat population will naturally decrease, he said.
Identifying the genes involved in cat personality could also help, by allowing breeders, for the first time, to select for traits such as friendliness and gentleness, rather than just looks, he said.
Skeptics remain Driscoll doesn't think spay and neuter programs will make cats any less friendly. For one, no studies have ever shown any genetic differences between house kitties and feral cats -- which are, after all, just domestic cats that fend for themselves and haven't been socialized to live with humans.
Moreover, simply too many cats with too much freedom are on the prowl for spay and neuter programs to change the entire gene pool.
"The population of domestic cats has been stable for a very long time," Driscoll said. "There's a lot of genetic inertia there. You can go out and spay and neuter all the damn cats you want, and the next year, they're all going to be back."