Biological Processes and Psychological Development
Although recent years have seen considerable progress in the understanding of how a fertilized egg gradually transforms into a fetus, an infant, a child, and eventually a fully functioning adult, the degree of complexity involved in this process has proven well beyond what most biologists and psychologists imagined few decades ago. Any successful theory of development must ultimately account for three fundamental features: the emergence of complexity of organization by differentiation, origin and range of variability across individuals, and the stability of form and function across generations. Epigenetics can be defined as the study of heritable changes in gene expression and function that cannot be explained by changes in DNA sequence or more broadly as the study of how the environment can affect the genome of the individual during its development, as well as the development of its descendants, without a change in the coding sequence of the genes. All developmental outcomes are co-determined by internal and external developmental resources.