The families of John Wayne Gacy and Ted Bundy appeared to be relatively normal, both of them were not only psychopaths but scary as heck, given they appeared to normal people going around killing people everywhere.
Psychopaths have no little to no sense of empathy. Its not worn on their sleeve or tattooed to their forehead. I guarantee you’ve met plenty of them and there are degrees of it. Very few are serial killers, but many are SOBs you want to avoid and not deal with.