1. © 2011 The McGraw-Hill Companies, Inc. Instructor name Class Title, Term/Semester, Year Institution Introductory Psychology Concepts Genetics

2. © 2011 The McGraw-Hill Companies, Inc. 2 Introductory Psychology Concepts: Genetics Chromosomal Abnormalities, a few examples: Down Syndrome: A cause of mental retardation resulting from the presence of an extra chromosome. Klinefelter’s Syndrome, or XXY syndrome: Males inherit an extra X chromosome. Associated with taller than average stature and impaired language skills. Turner Syndrome: Females have a missing X chromosome resulting in short stature and impaired spatial intelligence.

3. © 2011 The McGraw-Hill Companies, Inc. 3 Genetics: Dominant If a gene in the pair received by mother and father is dominant, the characteristic that it controls will be displayed. Recessive If a gene received from one parent is recessive, the characteristic will not show up unless the partner gene from the other parent is also recessive. Polygenic Effects When a number of gene pairs combine their influences to create a single phenotypic trait, this is known as polygenic transmission. Introductory Psychology Concepts: Genetics

4. © 2011 The McGraw-Hill Companies, Inc. 4 Behavior Genetics Heredity The transfer of characteristics from parent to offspring through their genes. Interaction of Nature Considering an individual’s innate qualities (nature) in determining individual differences in physical and behavioral traits. Nurture Considering environmental causes and personal experiences in the determination of physical and behavioral traits. Includes the influence of parents, siblings, family, friends, schooling, nutrition, and all other experiences to which a child is exposed Introductory Psychology Concepts: Genetics

5. © 2011 The McGraw-Hill Companies, Inc. 5 Twin Studies Understanding behavior based on the amount of shared genetic material Introductory Psychology Concepts: Genetics Two kinds of twins. Sperm Egg One sperm and one egg Zygote divides Two zygotes with identical chromosomes Identical twins (1 in 250 births) Identical (monozygotic) twins come from a single egg and sperm as a result of a division of the zygote. They have all of their genes in common.

6. © 2011 The McGraw-Hill Companies, Inc. 6 Twin Studies Understanding behavior based on the the amount of shared genetic material Introductory Psychology Concepts: Genetics Two kinds of twins. Fraternal twins (1 in 150 births) Two eggs and two sperm Two zygotes with different chromosomes Fraternal (dizygotic) twins result from two eggs fertilized by two sperm. They share only half of their genes.

7. © 2011 The McGraw-Hill Companies, Inc. 7 Heritability Estimates for Various Human Characteristics Genetics Heritability: Estimating the impact of genetic influence Heritability EstimateTrait Height Weight Intelligence School Achievement.80.60.70.40 Introductory Psychology Concepts: Genetics

8. © 2011 The McGraw-Hill Companies, Inc. 8 Genetics Heritability: Estimating the impact of genetic influence Introductory Psychology Concepts: Genetics Heritability Estimates for Various Human Characteristics Heritability EstimatePersonality Extraversion Conscientiousness Agreeableness Neuroticism.36.28.28.31

9. © 2011 The McGraw-Hill Companies, Inc. 9 Genetics Heritability: Estimating the impact of genetic influence Introductory Psychology Concepts: Genetics Heritability Estimates for Various Human Characteristics Heritability EstimateTemperament Emotional reactivity Activity level Sociability Impulsivity.40.25.25.45