It's most probably your approach. When chickens are first hatched, their instinct to fear anything approaching from above them is as intense as their need for food and water. The more you reach for them from up above, like a hawk diving down to pick them off, the more afraid they become of your hands.
This carries over to adulthood, and only consistent training can overcome this fear of your hands reaching for them. It helps to get down on their level, not easy for some of us in our last decades, but trying to pick them up by reaching down for them is futile.
It's possible for personalities to change over time, though, too. I have an SLW hen, five years old, who was among the first chicks I raised in a brooder on the floor. These chicks ran from my hands every time I tried to pick them up, and this hen has managed to mostly overcome her fear. She adores being cuddled, but she needs to be "caught". She comes barely within reach and waits until I slowly reach over and touch her lightly, then I slowly "walk" her toward me with my finger tips. It's so funny how coy she is while being so transparently a whore for cuddles.
After that batch, I began raising my chicks in a brooder elevated to waist level so I could handle them from the side. All of these chicks were tame from the beginning and remained so into adulthood. But even the most tame of them remain resistant to being picked up by reaching down for them. I need to get down on the ground to pick them up easily.
