The influence of genetics on training can scarcely be overemphasized. the goal of proper training is to optimize results within the limits set by your genetic potential. In order to avoid unnecessry frustration and discouragement, it is important you understand strength factors over which you have no control.

Muscular factors that affect muscle size and strength

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.

biomechanical factors that affect strength training

Limb length- Shorter limbs mean shorter levers, and a shorter lever has a biomechanical advantage. The resistance or weight is closer to the joint and is easier to lift than a weight that is further away. In general, if you have shorter limbs, you will be able to lift more weight than individuals with longer limbs, all other factors being equal.