I'm the first to admit that the current round of ethanol is not perfect. The rising demand for ethanol has put more land under cultivation, increased water shortages, and increased fertilizer and pesticide use. For all that, corn isn't really a great way to create ethanol, only producing 1.3 units of energy for every 1 unit put into its creation.
However, it is NOT responsible for the 40% increase in food prices over the last few years. It might seem like an easy target, but let's start with some logic, and then move into the solid figures.