I have multiple chickens that I've owned since birth, and they love me. They don't like being picked up and handled, but they will gladly let me pet them for minutes on end if I catch them in the right mood. The key factor is spending time with them, making them realize you are a regular part of their life. If you spend enough time with them and get on good terms with them, they will see you as "part of the flock." I even had a rooster who was really mean, but I had raised him since birth and have fed him 99% of his meals. He would always attack and harass anything that moved, but never me. I believe "don't bite the hand that feeds you" comes to mind. So just like with human children: love, care and plenty of treats is always a plus.