Distribution for gender, age, religion, family income and parents' education, land ownership and house type for the children participating in the study.

SES score was calculated from family income (0–3500 = 1, 3501–9000 = 2, 9001–20 000 = 3, >20 000 = 4) father's education (None = 0, 1–6 years = 1, 7–13 years = 2, Graduate or higher = 3), mother's education, land ownership (No = 0, Yes = 1) and house type (Kutcha/Pucca = 0, Independent house/apartment = 1).11 USD = 44.58 Indian Rupees (www.oanda.com, 8 April 2011, accessed 20 April 2012).2Pucca is a house made of burnt bricks, stones, cement concrete, timber or ekra. Kutcha is a house made of material other than the mentioned above, such as un-burnt bricks, bamboos, mud, grass or reeds. (The Ministry of Statistics and Programme Implementation in India).