We are a product of our DNA and life experiences
Our life experiences are the sum of what we have learnt to pay attention to. If we rightly or wrongly have learnt to pay attention to the things that scare us we have a scary life.
When our brains arrive they are effectively a blank page or template and it is our life and cultural experiences that put the writing on the page. Very little is set in stone when we arrive. Our genes are not completely fixed in influencing us. They are a starting point not an end point. Our genes may give us a disposition to something which may or may not transpire, in particular physical conditions. Emotional tendencies are much less fixed and part of the new understanding of the science behind human behaviour teaches us about the incredible plasticty of the brain, allowing us to change our responses to life if we take the time to understand what is going on for us.