The first reason is that we are born in Gods image and we are innocent when we are first born here because we know nothing. Therefor our automatic trait is innocence and innocence is usually good. Have you ever seen a baby steel or kill, no you haven't because they do not know how to do so. They learn harm or being bad from parents or other worldly influences and without that they are sin free.
They are born good. They may evolve into bad people . But they arent born bad people. Hitler wasn't born bad. He evolved into a bad man over time. They are born good not bad. They are born with many morals and like the nature vs. Nurture debate over time they evolve depending on their environment.
Babies are born good because they have gold hearts and they learn through socialisation with their parents. Babies from a year onwards learn what is bad and good, from then toddlers will then make their own decisions if they know what is bad or wrong in this world that they are born in which is full of deceit and lies and suffering
Babies aren't born evil. As a matter of fact, babies are shown to demonstrate moral behavior by the age of 6 weeks. It's pretty remarkable. Maybe in some cases babies are hard wired to become evil people, but it seems that most are inherently good and just need a good environment.
Beliefs are developed through influence, not through genetics. You are not born good, with either the ability to judge good or do good, likewise with evil. They only develop good or evil characteristics through cognitive and physical development where they take influence from their surrounding environment. You aren't born good or evil like you aren't born racist or sexist.
Babies are not born bad. Babies are born with a blank slate. As they experience things that slate is written on helping to mold the baby into the person he or she is going to be. Babies eat, sleep, and poop. They cry when they are uncomfortable. That is not being bad. It's just a stage of development.