For us being able to develop and change Ego and Alter, we need to have the mental capability for doing so. Which we obviously have, physically.
Both Ego and Alter can and do change heavily through life, and thus are strongly affected by culture, socialization etc. They can't change unbridled, though: There are multiple facettes of personality that are pretty stable over time (like in the Big Five model), ignoring traumata etc. And there are limits to our mental capabilities, just like there are for reasoning and other aspects of mind.
So, within the pysical borders our bodies give us, Ego and Alter can develop quite freely, heavily mediated by culture.
For us being able to develop and change Ego and Alter, we need to have the mental capability for doing so. Which we obviously have, physically.
Both Ego and Alter can and do change heavily through life, and thus are strongly affected by culture, socialization etc. They can't change unbridled, though: There are multiple facettes of personality that are pretty stable over time (like in the Big Five model), ignoring traumata etc. And there are limits to our mental capabilities, just like there are for reasoning and other aspects of mind.
So, within the pysical borders our bodies give us, Ego and Alter can develop quite freely, heavily mediated by culture.