Introduction to Abnormal Child and Adolescent Psychology. Robert Weis

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      Kirby is a 10-year-old boy who attends the third grade at a local public school. Kirby failed first grade and will likely fail again this year. Kirby’s reading is well below average, and he makes frequent mistakes in math. His writing skills are also poor. The school psychologist did not find evidence of a learning disability; however, psychological testing revealed below-average intelligence.

      Kirby is frequently disruptive and inattentive during class. His teacher stated that Kirby’s parents “just don’t care.” She has tried to contact his mother by telephone, but she usually does not return her calls and rarely follows through with her suggestions for home tutoring. Kirby will likely be sent to a remedial “special ed” class next year if improvements are not made.

      Socially, Kirby is awkward. He is larger and taller than his classmates. He is teased because of his size, his poor grades, and the frequent reprimands he receives from teachers. Classmates also make fun of Kirby because of his name, his old “Walmart clothes,” his poorly cut hair, and the fact that he always “smells like hot dogs”—due to his family’s wood burning stove.

      Kirby has few friends in his class. After school, he often hangs around with older kids at the junior high school. Kirby has been caught smoking on a few occasions and teachers also suspect some alcohol use. He is also beginning to pick on younger children after school.

      Kirby’s problems include poor academic skills, disruptive behavior at school, and rejection by peers. They can be explained using the three types of gene–environment correlation.

      If you were Kirby’s therapist, how might you use the concept of gene–environment correlation to intervene and help Kirby establish a new developmental pathway?

      Epigenetics

      According to the diathesis–stress model, children will develop a disorder only if they have both a genetic risk for the disorder and an environmental stressor to trigger its onset. Moreover, gene–environment correlations show that our genotype and our environment are not independent; we sometimes select environments that are conducive to our genes. A new area of research called behavioral epigenetics shows that environmental factors can also directly affect the expression of our genes and our risk for mental health problems (Hill & Toth, 2016).

      Recall that our genetic makeup consists of DNA, which is organized into genes and chromosomes in each of our cells. Genes direct the building of proteins that allow each cell to specialize and carry out its essential functions. These proteins influence our health, appearance, thoughts, feelings, and actions.

      Epigenetic structures consist of chemical compounds and proteins that attach to our DNA and turn genes on or off. These compounds and proteins are not part of our genetic code; consequently, scientists call them epigenetic (i.e., above the genome). When these epigenetic structures attach to DNA and regulate its expression, scientists say they have “marked” the genome. Although these marks do not change the DNA itself, they do alter the way in which cells use the DNA’s instructions. These epigenetic marks can be passed on to new cells when they divide. Moreover, epigenetic marks can also be passed down from one generation to the next.

      Epigenetic compounds can affect the expression of DNA in two ways (Image 2.4). In a process called DNA methylation, proteins attach chemical tags (called methyl groups) to certain portions of genes, turning them on or off. In another process called histone modification, DNA wraps either tightly or loosely around histones. Segments of DNA that are loosely wrapped can be expressed, whereas other segments that are tightly wrapped cannot (National Human Genome Research Institute, 2019).

      Environmental experiences can change epigenetic structures. Certain environmental factors such as diet, smoking, and exposure to disease have been shown to alter structures, leading to different expressions of the genetic code. Epigenetic structures are heritable. Although much of the epigenome is reset when parents pass their genes to their children, some structures persist and affect the child’s phenotype (Cicchetti, 2019).