What causes water molecules to have a bent shape according to the vsepr theory?
Ah, water. It is an oddity. The reason water has a bent shape is that the two lone pair of electrons are on the same side of the molecule. They really repel each other as they are only attracted to the oxygen atom in the water molecule. This repulsion of the lone pairs of electrons on the oxygen atom causes the bond of the hydrogen to the oxygen to be pushed downward (or upward, depending on your point of view). The hydrogen atoms are like the ears of Mickey Mouse, or like the shape of the dump you took this morning.