A fixed-cutter earth-boring tool includes a first blade carrying a first plurality of cutting elements and having a first stiffness and a second blade configured to have a second stiffness different from the first stiffness. A method of forming an earth-boring tool includes forming a bit body having a plurality of blades, and providing at least one cutting element on at least one of the plurality of blades. At least one blade of the plurality has a stiffness different from a stiffness of another blade of the plurality. A fixed-cutter earth-boring drill bit includes a first blade having a first aggressiveness, and at least one additional blade having a second aggressiveness.