i've always wanted to ask this...but the maximum pounds of muscle you can expect to add in a year is about 5- 10 lbs...is this really true?? they say that 10 pounds if you have perfect nutrition and you are a hard gainer. http://scoobysworkshop.com/gainingMuscle.htm
I went from 148 to 165 in one year (freshman year at college). I was very lean from being on the track team in High School. So I was a bit underweight.
I think who your mother and father were will be the largest determining factor in your abilty to gain muscle.