Biology

1. Epigenetics

1.1. The study of changes in organisms caused by modification of gene expression rather than alteration of the genetic code itself

1.2. A change in phenotype without a change in genotype

1.2.1. The genotype is the set of genes in our DNA which is responsible for a particular trait

1.2.2. The phenotype is the physical expression, or characteristics, of that trait. For example, two organisms that have even the minutest difference in their genes are said to have different genotypes.