Science of human development: seeks to understand how and why people and circumstances change/ remain the same over time: depends on theories, data, analysis, critical thinking, sound methodology. 5 steps of a scientific method (way to answer questions that require empirical (experience/ observation) research and data-based conclusions): being with curiosity, develop a hypothesis, test the hypothesis: gather empirical evidence, draw conclusions, report the results. Replication (6th step): repeating the procedures and methods with different participants: scientists study the procedures of other scientists, conclusions are revised, refined, confirmed. Nurture: environmental influences, beginning with the health and diet of embryos mother to family, school, community, society: aka. heredity-environment & maturation-learning, nature always affects nurture, and nurture affects nature. Alcoholism: begins with genes that create addictive pull that can be between overpowering and weak, genes/alleles for alcoholism has been identified on every chromosome except the y chromosome, nature and nurture varies by age and context.