What role does nature (versus nurture) play in the development and treatment of depression and obesity? While researchers have made great strides in identifying a number of biological underpinnings affecting both conditions, it is important to maintain a balanced view. As Laura Berk notes in Infants, Children, and Adolescents:
“Within the cell, a wide range of environmental factors modify gene expression (Strachan & Read, 2004). So even at this microscopic level, biological events are the result of both genetic and nongenetic factors” (53).
Phenylketonuria, a genetic disorder, presents an interesting example of the nature/nurture relationship:
PKU “affects the way the body breaks down proteins contained in many foods. Infants born with two recessive alleles lack an enzyme that converts one of the basic amino acids that make up proteins (phenylalanine) into a byproduct essential for body functioning (tyrosine). Without this enzyme, phenylalanine quickly builds to toxic levels that damage the central nervous system. By one year, infants with PKU are permanently retarded.
[…] If the disease is found, doctors place the baby on a diet low in phenylalanine. Children who receive this treatment nevertheless show mild deficits in certain cognitive skills, such as memory, planning, and problem solving, because even small amounts of phenylalanine interfere with brain functioning (Antshel, 2003; Luciana, Sullivan, & Nelson, 2001). But as long as dietary treatment begins early and continues, children with PKU usually attain an average level of intelligence and have a normal lifespan” (56).
The effective treatment of PKU with nutritional adjustment not only highlights the complex relationship between nature and nurture, but also the significance of appropriate diet and its potential to alter brain functioning.
Berk, L. (2008). Infants, Children, and Adolescents (6th ed.). Boston: Pearson.