What field studies environmental influences on gene expression that occur without changes to the DNA sequence?

• A. Genetics
• B. Genotype
• C. Phenotype
• D. Epigenetics

Answer: (D)

Epigenetics studies how environment shapes which genes are active without changing the DNA sequence. It looks at chemical marks, like DNA methylation or histone modifications, that wrap or expose genes and thus increase or decrease gene transcription. Environmental factors such as nutrition, stress, toxins, or early-life experiences can create these marks. Some epigenetic changes persist through cell divisions and can even be inherited, influencing traits without any change to the underlying DNA code. For example, maternal diet can lead to epigenetic changes in offspring that affect metabolism or disease risk, and identical twins can become phenotypically different because of different epigenetic patterns. In contrast, genetics focuses on the genes themselves and how they are inherited, genotype is the specific genetic makeup, and phenotype is the observable traits resulting from both genes and environment.