in school. By late elementary school, he has been suspended a number of times for fighting and being truant. In junior high school, Ramon associates with peers who introduce him to other antisocial behaviors, such as shoplifting and breaking into cars. By adolescence, Ramon rarely attends school and earns money selling drugs. At 15, Ramon is removed from his mother’s custody because of his antisocial behavior and truancy.
Rafael, the younger brother, also shows early problems with defiance and aggression. However, these problems do not persist beyond the early elementary school years. Although Rafael does not enjoy school, he befriends an art teacher who recognizes his talent for drawing. The teacher offers to tutor him in art and help him show his work. Rafael also takes art classes at a local community center to learn new mediums. Through these classes, he meets other adolescents interested in drawing and painting. Rafael’s grades in high school are generally low; however, he excels in art, music, and draftsmanship. He graduates with his class and studies interior design at community college.
©iStockphoto.com/Feverpitched
What accounts for Ramon’s struggles and Rafael’s resilience? Although there is no easy answer, a partial explanation might be the presence of protective factors at just the right time in Rafael’s development. Ramon’s path to antisocial behavior was probably facilitated by peers who introduced him to criminal activities. In contrast, Rafael’s peer group encouraged prosocial activities and the development of artistic competence. If Rafael’s teacher did not encourage the development of his talents until later in Rafael’s development, perhaps after he developed friendships with deviant peers, would he have followed the same developmental pathway as Ramon? Although we do not know for sure, we can speculate that these protective factors played an important role in his ability to achieve despite multiple risks (Masten & Cicchetti, 2016).
Most protective factors occur spontaneously: A teacher nurtures a special talent in an at-risk youth, a coach encourages a boy with depression to join a team, or a girl who has been abused is adopted by loving parents. Sometimes, however, protective factors are planned to prevent the emergence of disorders. For example, communities may offer free infant and toddler screenings to identify and help children with developmental disabilities at an early age. Similarly, schools may offer prevention programs for students at risk for learning disabilities. Even psychotherapy can be seen as a protective factor. Therapy helps children and adolescents alter developmental trajectories and promote long-term well-being (Masten & Kalstabakken, 2019).
Review
Risk factors interfere with the acquisition of children’s competence or their ability to adapt to their surroundings. Protective factors buffer children from risks.
Resilience occurs when children develop competence despite the presence of multiple risk factors.
2.2 Biological Influences on Development
How Can Genes Affect Development?
Genes and Chromosomes
Our body contains approximately 50 trillion cells, each containing our complete genetic code. The code is written using deoxyribonucleic acid (DNA). DNA is shaped like a twisted ladder, or double helix. The “ropes” of the ladder are made up of sugars (deoxyribose) and phosphates. The “rungs” of the ladder consist of pairs of chemical bases held together by hydrogen bonds. Their structures allow them to combine only in certain ways, forming our unique genetic blueprint. DNA instructs each cell to build proteins, which form the structure and characteristics of the person (Frommlet, Bogdan, & Ramsey, 2016).
Segments of DNA are organized into genes. A single human cell contains approximately 20,000 genes. If the genes in each cell were connected together, end to end, they would be approximately 2 meters long. To save space in the cell, genes wrap around special proteins called histones. Histones are important because they can turn genes “on” and “off” by binding to them in certain ways (Rutter & Thapar, 2015).
Genes are organized into strands called chromosomes. In typically developing humans, each cell contains 23 pairs of chromosomes, for a total of 46. Twenty-two of these pairs, called autosomes, look the same in both males and females. The 23rd pair, the sex chromosomes, differs in males and females. Females have two X chromosomes, whereas males have one X and one Y chromosome (Image 2.3).
Most cells form in a process called mitosis. In this process, chromosome pairs split in two and duplicate themselves. Then, the cell divides, forming two cells with 23 pairs of chromosomes each. The resulting (daughter) cells are identical to the original (parent) cell. Each cell contains the entire genetic code, but certain segments of the code are switched on or off, telling the cell its function: to serve as lung tissue, heart tissue, or other parts of the body.
Sex cells (i.e., sperm and ova) form differently, in a process called meiosis. Just as in mitosis, chromosome pairs split and duplicate themselves. Unlike in mitosis, however, chromosome pairs line up and exchange genetic material with each other, a process called recombination. Finally, the recombined chromosomes split into two daughter cells that are genetically different from the parent cell and divide again into sex cells. The result is that the sex cells have slightly different genetic information than the parent cells and only one-half the number of chromosomes. When sex cells combine during fertilization, each parent contributes one set of chromosomes and his or her genetic diversity to the offspring. Many genetic disorders arise when problems occur during meiosis. For example, children may inherit too many or two few chromosomes from each parent. Down syndrome typically occurs when children inherit an extra 21st chromosome during fertilization (Frommlet et al., 2016).
Neurotypical individuals have the same genes; the differences in people’s appearance come from slight variations in these genes, called alleles. For example, all people have genes that determine their hair color. Different alleles influence whether someone will be a blonde, redhead, or brunette. These alleles are usually inherited from parents or develop spontaneously as a genetic mutation (Nussbaum, 2016).
Many people erroneously believe that genes determine behavior. For example, newscasters may incorrectly report that researchers have discovered a gene responsible for sexual orientation or a gene that makes people behave aggressively. Nothing could be further from the truth. Genes merely form a blueprint for the body’s creation of proteins. Some of these proteins partially determine our hair color, eye color, or skin pigmentation. Others influence our height, body shape, and (sadly) our cholesterol. No gene directs behavior. However, genes can lead to certain structural and functional changes in our bodies that predispose us to behave in certain ways (Jaffee, 2016).
Behavioral Genetics
Behavioral genetics is an area of research that examines the relationship between genes and behavior. Behavioral geneticists use three approaches to identify the relative contributions of genetic and environmental influences on development. The first, and simplest, approach is by conducting a family study. In a family study, researchers determine whether a certain characteristic is shared by members of the same family. If the characteristic is partially determined by genetics, biologically related individuals are more likely to share the characteristic than unrelated individuals.
For example, researchers have examined the heritability of children’s intelligence using family studies. If we look at the light bars in Figure 2.2, we see that the correlations of IQ scores are higher among biological relatives than among nonbiological relatives. Behavioral concordance is expressed