Muscle belly length-this is the length of the muscle fibers, not including the attached tendons. If you have greater muscle tissue opposed to your tendon, you may have a greater ability to develop muscle size and strength.
Muscle fiber composition-fast twitch fibers tend to hypertrophy more readily than slow twitch fibers. If you inherited a high percentage of fast twitch fibers you will be more successful at strength and power activities, all other factors being equal.