12 Unit 1 Children and Families in Today’s World Copyright Goodheart-Willcox Co., Inc. explains why even identical twins who have the same structural genome are somewhat different before birth. How does the epigenome affect who people are? Although research is just beginning, the fol- lowing is what is currently known: • The epigenome is built through positive and negative factors from the environment. Positive factors cause the chemical compounds to turn on genetic potential— making the person all they can be. Negative environmental factors cause harm in all domains of growth and development. • Positive environmental factors include health, quality learning experiences, and supportive and loving relationships. Negative factors include toxic substances, poor health practices, lack of quality experiences with objects and people, and some stressors. Stressors are situations that cause worry and anxiety. (Throughout the text you will note mental health advisories mainly stemming from stress.) • Stress can be both benefi cial and harmful depending on the level of stress and how often and how long the body’s stress system is turned on (Figure 1.5). Having loving and responsive people in a person’s life reduces the effects of stress. Without these people, problems may occur even in later life. Heredity and Environment Combined For years, people argued about which factor affected growth and development more—heredity or environment. This argument was often called nature versus nurture. Of course, there is no way to study environment separate from heredity because the environment has to act upon the genes. Now, experts agree they work together. Following are a few examples of the interaction of heredity and environment: • Genes control height potential, but a proper diet is needed to reach this height. • Potential intelligence is inherited, but physical factors (nutrition and rest) and the quality of experiences determine whether the potential will be reached. • Basic social-emotional traits are inherited, but greatly affected by experiences. Heredity Affected by Environment In recent years, geneticists have discovered genes are not fi xed as once thought. The environ- ment in which a person lives, both before and after birth, can alter genes through their epigenome. The epigenome (eh-pih-JEE-nohm), which means above the genes, consists of chemicals that can turn genes on and off. Thus, the epigenome is like the operating system of the computer. The epigenome Figure 1.4 (Continued) How would the environmental impact be different in mass media if children… • have needed and accessible materials to meet their developmental needs versus find needed materials scarce and/or not accessible? • see content that is positive and safe for children versus negative and unsafe? How would the environmental impact be different in the parents’ workplace if the job… • has secure employment versus less secure employment with many closures and layoffs? • rewards work with wages or salaries that meet family needs and goals versus gives insufficient monetary rewards for work? • has one worksite versus requires frequent mobility? • is family-friendly (has reasonable work hours, grants parental leaves for new babies and severe family illnesses, has family benefits, such as child care services and family insurance policies) versus is not family-friendly?