How to raise girls?

So some time ago I had a chance to speak to two little girls, each one of them was 10 years old and they were close friends. I couldn't stop thinking about how different they were! One of them so completely stuck up, loud and obnoxious, the other one was very humble, more quiet and extremly intelligent for her age. I had conversations with her as if she was my friend! She was super nice too, while the first one would always make remarks to make herself seem better than everyone else. So my questions is: how does that happen? is it genes or pure parenting? How to make your daughter NOT stuck up..? What qualities and behaviors should be enforced? Thanks :)

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Aww first of all thank you for all the blue dust, I'm sure it will come handy one day :) Thankfully, I've never come across completely spoiled boys, maybe except in my early school years, but then I really didn't pay attention to them anyway haha ;) Yeah, I also believe parents have a big role in how the child will act, and I just hate when someone spoils the child so badly that it believes he/she is a gift to all of us walking this earth :/ Hopefully I'll do a good job with my son one day, but it seems frightening how much depends on the parents.. Oh well, I'll try my best :) thanks.

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