Human behaviour is, in so many situations, the 'cause' and not the 'effect'.

Every effect can also be a cause but every effect needs a cause and every effect is effected by what causes it, human behaviour is just part of a chain of cause and effect and cannot be the sole cause of anything so what you are saying leads no where. Conscious "decisions" are just the causal effect of effects that where caused that can effectively cause things to be effected but cannot cause their own effect because they are effected by both external and internal causes which ultimately causes them to be subject to effects which they cannot control.

No, no, no, no... It starts at the

It doesn't start anywhere, because it's a complex issue which is reliant on many different factors which shape behaviour. You could just as easily say it starts with quantum physics or with gravity.

you don't understand what is the cause and what is a means of observation

You don't understand that there is no one specific cause, both nature and nurture and neurons and hormones all play their part and none of them can be called the "root of behaviour"

What we are discussing here is which "mostly determines" personality

All of it does, there is no definitive way to quantify which one "mostly" determines it because it wouldn't exist without all of the fundamental factors necessary for it to exist, it's like saying "What mostly determines the size of your dick, it's length or it's width?"

If that's all true then we can't help but believe in free will so checkmate?

There is no scientific basis for free will, there is a scientific basis for a mechanistic and deterministic worldview.

It is a common phrase "The smarter you get the less you speak", and this is a fine example of that. I am not talking about quantity but specifically context. In your second refutation point you made some broad scientific claims and statements about neuroscience in which I can easily tell credibility is lacking.

Neurotransmitters and hormones are both are chemicals in the brain that carry messages throughout the body, so making the distinction between the two, as you did, and then throwing in completely unrelated matters such as preconceived religion and how one defines instinct, completely shows the huge problem with ethos (or lack of) through your whole refutation.

No, actually it's within my nature to struggle against the way of things.

Don't join the drones Nomen, fight your fate and master your destiny.

I'm glad to see someone presenting arguments which are not cluttered with ad hominem attacks, unlike other specific debaters. The main problem I have with you argument is that you claim the past, present, and future do not exist, however this statement is false. I believe a more accurate statement would be: "The past, present, and time, are all the same thing, when looking at the universe from an external view rather than internal"