All is really psychological
The debate between nature and nurture has raged on since the advent of psychology and particularly biology.
The fact is, as the Rebbe teaches, nature comes from the soul hence as he wrote to one doctor, how scientists feel they find a great treasure every time they find a physical (dna etc.) reason for something (in this case that happiness was the result of some chemicals in the blood stream, as if it disproves all supernatural, soul, psychological influence,) when the reality is, that it is the soul that produces the physical effects in the body.
I recently spoke to a psychologist and asked him if thought that bi-polar etc. was a chemical imbalance, he replied what I believe, that studies have proven, that chemical imbalances are a result of psychological imbalances.
In other words, what Chassidus teaches us, that our minds are the creators of our emotions.
So once we understand this simple fact, that our mindset, our beliefs, our desires, our belief in what is good or bad for us, sets up the emotional loves and fear – desire to attain, or stay away from something that will prohibit our desires, well the rest is very simple.
What do I mean?
Fundamentally speaking we are a composite of three souls:
Animal, pain vs. pleasure, as all animals act on this instinct.
Divine, good versus bad.
And finally a rational side which can discern between the two.