Don't Like Broccoli? A Receptor Gene's Variation Suggests An Evolutionary Excuse:
"Compounds known as glucosinolates are present in a variety of vegetables included in the human diet (especially Cruciferous vegetables), but these compounds can block the formation of organic iodine and the transport of iodine into the thyroid. Iodine is necessary for proper thyroid function, and in geographic regions where inorganic iodine levels are low, endemic goiter (enlarged thyroid) can arise in response to the need to maintain levels of thyroid hormone. In such circumstances, thyroid toxins such as glucosinolates can exacerbate problems with thyroid function. Deficiencies in thyroid function can result in retarded sexual maturation and mental retardation in low-iodine regions (typically, remote areas far from the sea)."
New research indicates that children containing certain genes are more sensitive to the bitter taste in various vegetables and avoid them. This paper argues that this is an adaptive survival mechanism, and that many of the vegetables people with the bitter gene avoid might impair thyroid function for peoples living far from the sea and therefore lacking good sources of iodine/salt.