O, that this too too solid flesh would melt, thaw, and resolve itself into a dew
Certain traits, like height and hair color can largely be explained through simple genetics: If both of your parents are tall with blond hair, chances are you will be too. However, not all genes are created equal and most traits are not controlled by a single gene. Instead, most traits, such as metabolism, personality, intelligence, and even many diseases, are much more complex and rely on the interactions of hundreds of different genes. The complexity doesn’t stop there. If it did, then identical twins would be exactly the same; but they are not. Although they tend to be extremely similar, identical twins can still differ greatly in health and personality. This is because, although they carry an identical set of genes, their genes may be expressed at different levels. Genes are not simply turned “on” or “off” like a light switch, but instead function more like a dimmer switch with a dynamic range of expression. The amount that a gene is expressed can differ from one person (or twin) to another and can even fluctuate within a single individual. The mechanisms by which these kinds of changes take place are extremely complicated and are influenced by a variety of factors including one’s internal and external environment. Epigenetics is the study of these kinds of changes and the mechanisms behind them.
