DANG, March 21 -- Wearing a huge Madal (Nepali hand drum) around her neck, Ganga Gandarva starts singing while her twin sister Jamuna accompanies her with the beat. Though their singing impresses everyone around, the expression on their mother, Rupa's face barely changes. With a painful look on her face, Rupa says, "They often ask me, 'Mummy, when will we see the world?' But I am speechless," adding, "They are already so happy, I wonder how happy they would be if they could only see the world."

Ganga and Jamuna were born with visual impairment. Their elder sister Manisha, 10, is not just visually-impaired but also struggles with speech. Her bed is the world to her as she rarely gets out of it. She cannot even walk properly. "She can't se...