I guess one question is what do you mean by "natural inclination".

Humans are clearly capable of murder. They also, clearly, engage in it quite rarely (regardless of the degree of law & order around, I might add). Evolutionary speaking, the capability to murder is beneficial, but needs very strong constraints on it -- a tendency to murder those (of your species) around you is likely to wash out of the population pretty quickly.

So yes, there is a biologically hardwired ability to murder, but there are also hardwired brakes on it. These brakes are pretty powerful.