Kyphosis (a forward curvature of the upper spine) is a common issue. To fix this, it's easy to gravitate to pull-ups or chins as a default major movement. But that's a mistake.
Based on the body's starting point, the overhead position can be very harmful to the shoulders, which will present immobility in the presence of a kyphotic spine. Those with kyphosis are far better off doing more rowing motions than pull-up motions.