Velcroman1 writes: The nature versus nurture debate just took an unexpected turn — thanks to pollution. Increased exposure to the toxic chemical mercury can affect sexual preference in certain species of birds — inducing homosexuality, a new study has revealed. Peter Frederick, an ecologist from the University of Florida, and Nilmini Jayasena from the University of Peradeniya in Sri Lanka found that male American white ibises that consumed methylmercury, the most toxic and easily digested form of mercury found in the environment, were more likely to pair with other males."We knew that mercury was likely to affect reproductive hormones from an earlier study," Frederick said, "so we suspected some aspect of reproduction would be affected. We had no clue that mate choice might be involved," he added.