Final answer:
C.H. Waddington highlighted genetic assimilation and heritable epigenetic changes as central to epigenetics, focusing on how environmental factors influence gene expression and traits across generations.
Step-by-step explanation:
According to C.H. Waddington, two concepts that were central to the study of epigenetics were genetic assimilation and the idea of heritable epigenetic changes. Genetic assimilation refers to the process by which phenotypic changes, which initially arise in response to environmental conditions, become encoded genetically over generations. Heritable epigenetic changes involve modifications in gene expression that are not changes to the DNA sequence itself but can be passed down to offspring; these changes may arise due to factors including histone modifications and DNA methylation.
Epigenetics demonstrates how environmental factors and individual behaviors can influence gene expression and the phenotypic traits of individuals, with potential effects on subsequent generations. This includes the impact on growth and development from exposure to conditions such as smoking or trauma, and the possible intergenerational legacy of such exposures.