The set of observable characteristics of an individual resulting from the interaction of its genotype with the environment.
If our genotype represents all of the possible potential manifestations of an organism, the vast majority of which are unseeable, then our phenotype is what the world sees. It is the physical manifestation of our genotype – quite literally how we look.
We have some significant control over how this plays out to the degree that we develop what we have, but we’re not changing our basic genetic blueprint. It was the hand we were dealt at birth, and it’s ramifications significantly define who we are.
Take actors for example. The arc of their careers is determined to a large degree by their phenotype. Lee Van Cleef was never going to play soft male roles – his phenotype said this is a cold, cunning and cruel man. It didn’t matter if that was his true personality or not. Which leads to the question: Does our phenotype actually determine who we become? If we look mean, do we become mean? If we look kind, does that necessarily represent who we are?
I think the answer is clearly no – humans are way too complex for that. The old truism “don’t judge a book by its cover” indicates that this was a lesson worth passing down from generation to generation, no doubt as a safety mechanism for survival.
But still, clearly phenotype is our destiny to some degree. Some people are breathtakingly beautiful, most are not, and some are (at least by the standards of the surrounding society) downright ugly. No amount of grooming or exercise or plastic surgery is going to change that. We can work to maximize what we have, but we cannot become what we are not.
The really weird thing is, I’m not sure any of us really has that clear an idea of how others interpret our phenotype. What others see when they look at you is most assuredly not what you see when you look at yourself.
Which brings up another interesting question: To what degree does inner will and intent shape how others interpret your phenotype? My guess is that, although it’s not something objectively seen, it most definitely is something subjectively sensed.