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.
What is a metallic taste? A metallic taste is a distorted sense of taste in your mouth. A metallic, bitter or foul taste in the mouth is also referred to as dysgeusia. A lack of or change in taste can be due to anything that interferes with the normal taste process. Taste and the flavors you perceive are the result of a combination of the sense of smell and sensory neurons in your taste buds, which tell the brain what substances you taste (sweet, salty, sour and bitter).