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.
Metallic Taste. Sometimes an iron or metal taste in your mouth can be caused by vitamins . . . are you taking a vitamin that is rich in Iron . . . this can do it. Take the vitamin with a glass of milk or look for a multiple vitamin that is NOT iron enriched.