Genetics as a science is somewhat new on the scene. Though there were contributions from Pythagoras, Hippocrates, and Aristotle, modern genetics is said to have begun with the work of the Augustinian friar Gregor Johann Mendel. His work on pea plants, published in 1866, established the theory of Mendelian inheritance.
Since the acceptance of modern genetics theory around 1925, it was established that directly inherited genetic traits play a major role in defining who we are.
Epigenetics and Inherited Behavior
The new science of epigenetics is changing how we think about inherited traits. Epigenetics explains changes in gene function that are not mirrored by underlying changes in DNA sequence. It is related to the idea of gene expression- that organisms with the same DNA can manifest different traits, based on the influences of unique external and internal environments.
Epigenetics can be defined as the study of changes in organisms caused by modification of gene expression rather than alteration of the genetic code itself. Epigentic changes are heritable, and this is why our proclivities for certain behaviors shared by our parents are more than just learned. By inheriting genes with certain sequences “hidden” due to methylation, we can become pre-disposed to certain behaviors, levels of stress hormones or neurotransmitters, dietary choices, and even certain diseases.