Gallstones form in the gall bladder for a variety of reasons:
Stasis - If the gall bladder does not empty completely, the resulting "stagnant" bile may crystallise into gallstones. This occurs most frequently during pregnancy; and in one way explains the female preponderance in gallstone sufferers
Composition - Bile is composed of bile salts and cholesterol. If the balance of constituents is altered this may lead to crystalisation of the constituents out of solution and the formation of stones
Infection - Infection within the gall bladder by bacteria may provide a "nidus" for the bile constituents to crystallise upon
Whatever the route taken, once gallstones form they will remain. This is due to the "scarring" which the gallstones cause within the gall bladder. This further reduces the ability of the gall bladder to expel bile and promotes the formation of further stones. Hence the fallacy of "just removing the stones" which is often suggested as a treatment option.
Patients without a gall bladder do not miss it, only the pain or complications.