It's an age-old question that might now be starting to see light, but the answer may not be quite what you'd expect.
The question is what influences us more throughout our lives - our biological makeup (nature), our parents or our peers. The answer is definitely not set in stone and far more in-depth research will need to be conducted before we're sure, but it looks like mommy and daddy actually play the least influential role in shaping your life, followed by your peers and then of course by nature, which accounts for around 50 percent of what makes you You.
If we believe this then it actually means we have far more control over what kinds of people we are shaped into later in life than we thought before, but this is wholly dependant on the kinds of people we choose to associate with as children.
It's funny, it's like mothers somehow knew this - I'm sure we've all heard them saying: "Choose your friends wisely". Well she was right; getting involved with the wrong crowd is a bad idea.
This also explains why siblings (who also influence each other less than their peers) can be so vastly different to one another. The research found that shared home experiences (involving both biological and adopted siblings) played a very minimal role in shaping the personalities of the children. When siblings shared a similarity, it was found that its roots were more likely from shared genetic inheritance than shared home experiences.
Not to say that parents have no influence on their children, they most certainly do, but it's very interesting to note the surprisingly low level.
Furthermore this research should bring an end to the debate of whether leaders are born or bred; they are both.