Some people think it is the environment you grow up in that makes you who you are whilst others think that you are who you are and that is it.
It is a question as old as time.
I don’t think there really is a answer either.
Both form your personality, you start as a blank slate and people add things to you and as you grow older you filter out what pieces of that stay and which go. The way you are treated growing up will mold how you act, speak and hold yourself but you will naturally just turn into a fully formed person no matter what.
Everyone is different and not all people tend to react to the same upbringing as others but things your parents expose you to at a early age can form the basis of your likes and dislikes, it’ll form a biased opinion on likes and dislikes at a early age too that sometimes it takes a lifetime to change. If your parents hold strongly to a political view or world view and you don’t get it challenge it can be adopted as yours until you challenge it, as long as it is challenge at a young age then nature does its thing and helps you mold it on your own.
I don’t really know much about biology or anything about human nature but I feel like there is a certain part of us that is us from birth and that is why some of us swerve severely against the norm and do good and bad things without it overly being the fault of a parent/guardian or the environment they were born in. Things that happen to us have as much effect as the people around us.
It is a hard one really.
Honestly I think it is just a mixture of both.