What is it that determines the kind of person we come is it the environment or our family? The environment has been at war with family for years just because we have different families with different ideologies of how things should be, a good example is when you are comparing a black family with a white family there is always a difference.
The family thing
The first thing that will determine the kind of person you will become is family because blood is one of the most sacred and purest things before you exit there have been thousands of people and generations that come together before it gets to you and that is why some people can predict the kind trait you might have based on your family history. My tribe(Yoruba) will always make inquiries about your family before they get married to you or have anything to do with you.
Another powerful thing is nurture, how you were nurtured when you were young. Our younger selves are always very easy to mold and no matter the blood if you fall into the wrong hands when you are young and those hands mold you it will be very difficult to change. That is why you see that childhood trauma always has a greater effect and damage most times.
Environment thing
We are exposed to the environment at different ages and to some people, it can be early for them, environment easily molds them into what they are not, the exposure to the environment can come from a bad class teacher, bad neighbor, or neighborhood, bad friends and the most powerful one internet. If you are not lucky to encounter any of this at an early stage it might change you as a person.
Each of these factors affects us over time and gradually fight against everything our parents taught us or everything we believe in changing us into the person we thought we could never be.
The collision
The truth is that both environment and family  will have a great impact on who we are going to be but our blood and the morals our family use to nurture us will always fight against the negative side of the environment. Our foundation must be strong to win against the environment.