The Hardy-Weinberg principle is not generally found in nature because it requires certain conditions in an environment. These conditions are the absence of the things that can cause evolution. In other words, if no mechanisms of evolution are acting on a population, evolution will not occur--the gene pool frequencies will remain unchanged.
Some pregnant women experience a metallic taste in their mouth during the early stages of pregnancy, because of the hormone changes. It's also fairly common to crave certain foods, or go off certain foods, and have a heightened sense of smell.
Is the taste in your mouth like metal? A metallic taste in your mouth is a some what common symptom, and metal tasting is typically not a serious problem. Your perception of a weird metallic mouth taste can be due to an assortment of factors. However, the most common causes of that bad taste of metal in mouth are medications used for treatment of: antibiotics.