I think there are many other factors that would affect the way someone with sociopathic genes/tendencies might behave or manifest themselves. I sometimes like to use the example of someone with Down Syndrome. I actually have relatives that have Down Syndrome -- one blood and the other adopted. It's interesting to see the blood relative. He does sort of look like the rest of his family, his siblings and his parents, but he also looks unmistakably like his adoptive sister who also has Down Syndrome. In fact, most people would probably say he looks more like his adoptive sister than his blood siblings -- unless the observer was intentionally trying to look past some of the more obvious Down's markers such as distinctive facial features, body shape, etc.
Down's is an interesting condition. Throw an extra chromosome in there, and it affects the way seemingly every other chromosome is expressed. It's almost as if you take the raw genetic material and put a very distinctive mask over it, a sort of interpretive gloss that takes what was lying beneath and distorts it -- minimizing or maximizing or otherwise twisting it to something else, like when the face of a plastic doll melts.
I sort of think that sociopathy is like this. My personality resembles my siblings' quite a bit. It also resembles those of other sociopaths a good deal and in ways that are in some ways more poignant because of the relative rarity in the general populace. It's amazing to me how much I can share in common with strangers -- with people who are of different genders, ethnicities, races, nationalities, ages, etc. But I am not just like every other sociopath. From what I have seen of us we are all very different. But there is no mistaking a certain family resemblance.