Clinically, psychopathy seems to be related to brain measurable brain dysfunction. Sociopathy is slightly fuzzier, but there are established clinical questionnaires that are used for diagnosis, and they seem fairly reliable.

My suggestion is that the political feedback loops we have now - many of which are fall under that thing called "economics" - reward and enforce sociopathic behaviour in corporate and political contexts. Individuals who are that way inclined find it easy to thrive. Individuals who aren't, don't, but may find themselves acting in ways that perpetuate that culture in opposition to their private values.

Pre-university education matters too, but that's a different topic.

Left/Right is a one-dimensional measure for a multi-dimensional phenomenon. You can of course have Left-wing sociopathy. But there's not so much of it around at the moment and it's not so visible, because active sociopaths will go where the power is - and that's not currently on the Left. At the moment there isn't enough juice in the Left to keep the crazies happy there. It's true this might change in the future.

In practice the distinction is between empathetic and exploitative behaviour. Currently rather a lot of the latter has pooled on the Right.