Some people can roll their tongues, others can sing on key, and others can’t do those and other things. Beyond those sorts of traits, even identical twins aren’t completely identical, and other factors come into play that contribute to a person’s uniqueness– environment, differences in upbringing and perceptions, brain development, dietary choices, chemical imbalances, and so on.
The twins I know are fraternal, so physical, facial likeness doesn’t exist. They differ in personal habits and preferences and points of view as well, but they appear to be each other’s best friend and confidante.
Apart from twins or triplets, etc. and differences in physical appearance and even vocal inflections and tone, each of us is our own collection of behaviors and perceptions, products of our upbringing, of parental guidance and socializaton or lack thereof. It’s like we each arrive with our own specialized software, slightly or greatly varied, that informs how we receive external stimuli, how we see and hear things, and how we respond and react and make decisions.
3 Cents' 