There is no such thing as naturally strong... there might be some genetics in how quickly you can gain muscle strength but no one is born strong. To think of it conversely, if a limb becomes paralyzed, that limb will undergo extreme muscle atrophy no matter who it is. Also, they listed as a mean 83kg for bench press for the "upper third". This is not a very large amount of weight and is easily within the genetic limits of the grand majority of men.