It is clear that certain traits are handed down to us by our parents and unfortunately our ablility to grow muscles beyond certain limits is no exception. That doesn't mean to say hard work and carefully planned training won't have a positive effect on your physique - it just means that some people will inherit a greater abundance of the favored physical characteristics than others. Not everyone possesses the physical traits to become a champion, but you can work wonders with the raw material you do possess. How responsive you will be to physical stimulation can be predicted to a certain extent by examining your somatype or natural body shape. Basically, there are three recognized body types: 1. Endomorphs - these individuals tend to be squat with a round torso, thick neck and short limbs. 2. Mesomorphs - these individuals tend to be musclar with broad shoulders, powerful chest and limbs and little body fat. 3. Ectomorphs - these individuals tend to be slim and are usually tall with little muscle and body fat. The ideal bodybuilding physique tends more towards the mesomorph with broad shoulders, narrow hips with arms and legs of medium length. Two further inherited features have a role to play in determining muscle building potential, and these are muscle fiber density and neurological efficiency. Fiber density determines the size potential of a muscle while neurological efficiency refers to the relationship between the nervous system and muscles. This is relevant because, in all out effort genetically blessed individuals have the ability to activate up to 50% of the fibers in a given muscle compared to the average person's 30%. This allows greater scope for stimulating growth. The fact that there is no easy way to measure fiber density or neurological efficiency is actually a blessing because the incentive remains for all of us to train hard and strive for improvement. Only a tiny minority of people have the genetic tools to become champions but the rest of us can go a long way to fulfilling our own personal goals.