If corn is used in biofuels it can not be used as food. This is a fact. The laws of economics dictate that when you lower the supply of something then its price will go up. If there is less corn available for food because of ethanol, the price of corn for food will increase.
When the demand for a certain product (corn) increases the price will increase. This has to be the first rule of economics. If a large amount of people start to buy corn for bio fuel then food made out of corn and other substitute foods will increase in price. Simple.
Because the climate has made for mediocre crops and developed countries are pushing for more use of biofuel its adding to world hunger and increasing the cost of the food because the farmers would rather get paid more for the crops used for energy. As a result the poor can not afford the food or the fuels.