Do you mean thin legs? if so, then yes, different people have the predisposition to have varying amounts of strength, but i know some very wirey people who are incredibly strong. Most long distance runners are very slim and also very strong. And one of my friends is a body builder and has sparrow legs! his strength is mainly in his torso, but that's partly because he focusses most of his training there.
Maria Sharapova has been reported to have grown 2 more inches in height and she has very long legs....can't say much more as this is a family site...he he....
Of course. You can be 'wiry', i.e. skinny but tough and strong - look at Houdini! Look at many a champion lightweight boxer! Big muscles are not necessarliy stronger than small ones. Size of muscle tissue doesn't matter, it's strength, tightness and endurability that counts.