A person's character can be defined by a lot of things, their upbringing, the friends they keep, their parents, people they grew up with, etc, but at the end of the day, it all boils down to one person, you... You get to make the choice if you want to be good or bad
And the reason why I say this is because I'm using myself as an example. Luckily for me I grew up in a very religious and loving home, both my parents were present in my upbringing and I basically had everything (or almost everything) a child needed to grow up to become a good person.
But then there was the issue of the environment I grew up in. You see, it wasn't the best of places to raise a child, and I basically spent all of my childhood there. Everyday came with a new problem somewhere, either a teenager touched a child in an inappropriate way, or two grown women were fighting naked over a man.
It was always something new and crazy and I remember at the time, the majority of the kids my age were kids that I considered to be bad kids because they were doing things they shouldn't be doing at age.
There was a time I tried forcing myself into their circle but the moment I realized the kind of kids they were, I immediately knew they weren't for me, I made my choice. So I did the only thing I could do at the time, I made friends with kids that were two, three years younger than I was and I remember my dad didn't like it at the time because he felt I was way too old to be friends with those people, but what he didn't realize at the time was that the kids my age weren't the kind of kids he would have wanted me to be friend with either.
So at that young age, I found myself at a fifty-fifty position, where half of my life had the good things, the good morale in it (which was my family), while the other half of my life had the bad things in it (which was the bad friends participating in activities kids their age shouldn't be participating in)... I had to make a choice, and even though I was young, I knew the right choice to make, I knew not to be influenced by the bad side, I made my choice.
And this is why, although I do agree that a child's upbringing and the company they keep does play a vital role in the kind of person they eventually turn out to be, I still think that at the end of the day, you becoming a good or bad person is a choice you make for yourself by yourself while taking into accounts everything happening in your life, evaluating them to know what you should follow and what you shouldn't follow.
Another example is the story of a guy that I told a while back, who used to be a fraudster but later became a devoted Christian. The guy, is still devoted to his faith even till this day. This is someone whose entire friend group at the time consisted of fraudsters, cultists and everything bad that you could think of. His brother is still a cultists till this day, terrorising people in the street every now and then, yet, he remains devoted to his faith, making sure to go to both weekly and Sunday services while clenching his Bible in his chest for everyone to see everytime he walks by.
He is a true example that even when all the odds are against you, you can make a difference, you can learn to be good by taking a different path and not be influenced by the things either in your life or around your life.