Frequently, it is a genetic trait and you will be able to see who in the family you inherited it from. Older patients with weak chins usually notice their necks aging before the remainder of their face. Because they have very little definition in their jawline to begin with, a little aging (which means you lose definition) shows up very early. Chin implants help define the chin and jawline. It is a very simple, easy procedure requiring only 4-7 days off work.
One "rule of thumb" to evaluate yourself for this is to visualize, on your profile, a vertical line from the point where the bridge of your nose meets your forehead. If your chin falls behind the vertical line and does not touch it, you may be a good candidate for a chin implant. A male chin may even project beyond the vertical line. My personal philosophy for chin implants is that men should have a strong, masculine jawline, but not women. For women, you can easily improve your chin and jawline definition while maintaining a clearly feminine appearance.