Nature vs. Nurture: Genes, DNA & Behavior

• Nature pertains to genetic inheritance and biological determinants.
• Nurture involves environmental impact, experiences, and upbringing.
• Nature and nurture interplay to mold human development, behavior, and traits.

Historical Context

• Selective breeding has been used to enhance desirable animal traits.
• Gregor Mendel's work with pea plants established the basis for modern genetics.
• The structure of DNA was identified in the 1950s by Watson, Crick, and Franklin.

Genetic Basics

• Genes are composed of DNA segments coding for proteins, influencing behaviors and traits.
• The genome constitutes a complete set of an organism’s genes.
• The human genome contains roughly 20,000–21,000 protein-coding genes.
• Non-coding DNA regulates gene activity.

Key Concepts in Genetics

• Genotype refers to an individual’s inherited genetic makeup.
• Phenotype is the observable expression of the genotype.
• Environment includes all external factors to genes like experiences, upbringing, and social interactions.

Five Key Relationships in Development

• Genetic material is passed from parents to offspring, ensuring genetic diversity.
• Genes influence physical and behavioral traits through gene expression, regulated by genes.
• Dominant alleles mask recessive ones.
• Environmental factors influence how genes are expressed.
• An example involves Phenylketonuria (PKU), where a strict diet averts intellectual disability.
• Children actively shape their environments based on their traits and behaviors.
• Outgoing children solicit more social interaction than shy children.
• Environmental factors can alter gene expression without changing the DNA sequence via epigenetics.
• Methylation, due to environmental stressors, silences genes, affecting behavior and health.

Genetic Diversity and Inheritance

• Chromosomes are shuffled during gamete formation through Random Assortment.
• Chromosomes exchange DNA segments, increasing variability through Crossing Over.
• Changes in DNA that can be harmful, neutral, or beneficial are mutations and drive evolution.
• Females have XX chromosomes whereas Males have XY chromosomes.
• The father’s sperm determines the child’s sex (X or Y).

Polygenic Inheritance

• Most human traits are influenced by many genes (polygenic), not just one.
• Intelligence is linked to over 500 genes.

Gene-Environment Interactions

• The MAOA gene interacts with childhood maltreatment, influencing antisocial behavior.
• Parents’ genes influence the environment they provide for their children, known as nurture.

Epigenetics

• Epigenetics is the study of how environmental factors influence gene expression.
• Methylation silences genes, altering their activity.
• Rat pups with less attentive mothers showed altered stress responses due to changes in gene expression.

Applications of Genetic Knowledge

• Carrier Testing identifies individuals carrying genes for disorders.
• Prenatal Testing screens for genetic disorders during pregnancy.
• Newborn Screening tests for conditions like PKU to prevent developmental issues.
• Genetic testing raises questions about privacy, discrimination, and the interpretation of results.

Key Takeaways

• Development is a dynamic interplay between genetics and environment.
• Genes provide the blueprint, but the environment shapes how genes are expressed.
• Epigenetics demonstrates environmental factors can have lasting effects on gene expression.

Explore the roles of nature (genetics) and nurture (environment) in shaping human development and behavior. Learn about the historical context of genetics, including selective breeding and the discovery of DNA structure. Understand key concepts like genes, genome, genotype, and phenotype.