Does our environment make us who we are? Or are we inherently different?

I think you define yourself. But what you are exposed to certainly plays a role in building your character. I, for example, was raised in a small town surrounded by simple-minded people. These people included my friends, acquaintances, and even family. Yet I always knew deep down that there was more to this whole ‘life’ thing. I began filtering the material given to my brain.
Imagine your character as a house. Society and media and family will begin handing you wood for your house. You as an unique individual choose which wood you want and don’t want. Does that make sense?
I began tossing away the philosophy my parents taught me(they think the world revolves around money) and started absorbing things I found on the internet, in the world, and within my own thoughts. When I was told the key to life is money, grades, and college, I rejected it and replaced it with happiness, experience, and love.
Bottom line, I think everyone is born with character imbedded in them. But, their environment can help or hinder the size of their character.

In an absolutely perfect sense of this situation with absolutely immutable variables in exactly the same fashions, we would all be the same.

In the sense that you are describing, you have left out many variables, so we can clearly say no. Many would experience the arena around them in similar fashions, but the innate way that each of us is born to perceive would shape those experiences and cause differentiation. Each person is dappled with minute differences that shape the contours of our lives. It is too encompassing to claim that people are born with innate levels of anxiety, pacificity, aggression, and malaise, but genetics seem to point to those levels being absolutely true in many manners.

We would definitely not be mental clones. The short answer, potentially, is that humans are inexplicably amazing and diverse in their perceptions of experience.

Everything is influenced

I’d say we would be different, people interpret things in different ways, we are naturally stronger in certain areas while weak in others. You have instinct and genetic disposition that a baby is born with, these variables effect how they process information, and people are often inclined to replace their nature with external knowledge in varying degrees and varying subjects.

I’d say we would be different, people interpret things in different ways, we are naturally stronger in certain areas while weak in others. You have instinct and genetic disposition that a baby is born with, these variables effect how they process information, and people are often inclined to replace their nature with external knowledge in varying degrees and varying subjects.

we would still be different, i know its just a hypothetical experiment but it would be impossible for us to have the same experience seeing as how our perspectives have a huge impact on our experiences. although experiences and belief systems ties together, the believer chooses what to believe, thus the believer chooses his perspective, therefore you can say the believer chooses his experience “in some sense”…

Its a very complex relationship – the environment can make the body turn off and on genes, and the genes that are off and on can influence how you interact with the environment. Essentially the paradigm comes down to;
You are not separate from the environment.

You cannot separate yourself from the environment, just as you cannot leave Earth’s gravity. It will always influence you, the way it influences you will change how you react to the environment.

nature vs. nurture. I bet there are lots of HE threads about this and there is also a lot of psychological research about it.
or you could think about it from an existentialist perspective: does essence precede existence or does existence precede essence?

No, we wouldn’t be. I believe our brains determine our personality, though it’s a complex mix of neurology, physiology and genetics.