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Epigenetics is the study of how environmental factors can influence the expression of genes without changing the underlying DNA sequence. This field examines how the same genotype can result in very different phenotypes, providing a framework for understanding how experiences and environment can impact health and behavior.

Epigenetics

Some of the observed epigenetic modifications include:
- Methylation
- Histone modification
- Phosphorylation

Types of Epigenetic Modifications

One of the most common studies involving this topic involve studying how relative deprivation can alter health. Essentially, poverty can increase risk of mental health by altering gene expression.

Epigenetics and Socioeconomics

Accumulated stress (allostatic load) can affect a person's long-term health, especially if it occurs while young. This can effect people physically and mentally. As such, many epigenetic changes are attributed to this phenomena.

Long-term Effects of Allostatic Load

Identical twins originate from a single fertilized egg that splits, meaning they share the exact same genetic material. Despite having identical genes, there is incredible variability in how their gene expression unfolds throughout their lives. For example, one identical twin might develop a disease, such as cancer, while the other does not. Although they possess identical genotypes, their unique environmental interactions over time lead to different epigenetic expressions and differing phenotypes.

Example of Epigenetics in Identical Twins

The epigenetic perspective offers a very different view of gene-environment interactions compared to the range of reaction. In the range of reaction model, a person's genotype is viewed as establishing fixed, limited boundaries for potential development. In contrast, epigenetics asserts that the genotype is not rigidly fixed and limited; instead, environmental factors can flexibly alter how the same genetic information is expressed into different phenotypes over time.

Comparison of Epigenetics and Range of Reaction

Two genetically identical mice are raised in different environments. Mouse A is raised in a standard, quiet cage. Mouse B is raised in an 'enriched' environment with toys, social interaction, and regular exercise. As adults, Mouse B shows significantly lower levels of anxiety-related behaviors and better memory performance than Mouse A, despite having the exact same DNA sequence. Which of the following principles best explains this difference in outcomes?

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