Angels were perceived a long time ago when people used to think of the universe as divided into three distinct compartments -- earth, heaven and hell. With the perception of visits to earth from heaven and hell, they could only visualize people coming from heaven as having wings. With a pre-conceived thought of beings appearing with wings, they manifest in this dimension according to this picture. This suggests guardianship and for certain souls who care for children, grow these wings because there are always children who expect to see them.