Sociopaths are people who once functioned like normal people, but due to a trauma of some kind, be it mental or physical, lack an ability to properly feel empathy.
They HAD both feelings. And lost them.
Not true. A sociopath's development of emotions was stopped or unfinished. It's like getting half a math lesson - you won't know what any of the shit is. It is similar to language. If you don't learn a language by the time you are a teenager you never will. (Not another language, I mean a first language.)
It is in base human nature to both love and hate. Neither are learned. But both can be expanded equally through experience.
They HAD both feelings. And lost them.