Hereditary Influences on Development

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Hereditary Influences on Development

• Chapter 3

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Outline

• 1. Genetic Principles
• 2. Genetic Diseases
• 3. Genes X Environment

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Genetics

• Each cell in the human body has 46 chromosomes
  (23 pairs)
• Chromosomes are filled with DNA
• Genetic Blueprint

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Genes

• Specific segment of DNA, responsible for the
  production of a specific protein
• Allele Part of a gene 2 alleles per gene

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Genes

• Work in pairs
• Homozygous (Same)
• Heterozygous (Different)

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Basic Terminology

• XX Female
• XY Male

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Genes

• Genotype
• Set of genetic traits a person inherits the
  genetic blueprint
• Phenotype
• Set of traits a person actually displays

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Genes

• Dominant Genes
• Recessive Genes

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Genes

• Example of Dominant and Recessive Genes (eye
  color, hair color)

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Chromosome Abnormalities

• An error occurs during cell division
• Downs Syndrome (Trisomy 21), an extra 21st
  chromosome
• Any changes in genetic info (extra or less)
  Abnormality

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Sex Chromosome Disorders

• 1. Turner Syndrome X_
• 2. Kleinfelters Syndrome XXY
• 3. Fragile X xX or xY

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Single Gene Defects

• 1. Autosomal Recessive
• Inherit recessive allele from both parents
• E.G. PKU

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• 2. Autosomal Dominant
• Only need to inherit 1 allele, from either parent
• E.G. Huntingtons Disease

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• 3. Recessive genes on the X chromosome
• Sex linked
• E.g. Hemophilia

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Sickle Cell Anemia
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Think about yourself

• How sociable are you?
• How athletic are you?

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Models of Gene-Environment Interaction

• Reaction Range (Gottesman)
• Degree to which variations in the environment
  influence genotype

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Behavioral Genetics

• Robert Plomin
• Studies the influence of genetic factors on
  behavioral traits

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Gene-Environment Correlations

• Scarr and McCartney (1983)
• 1. Passive
• 2. Evocative
• 3. Active

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Behavioral Genetics

• 1. Twin Studies
• MZ vs DZ (Identical vs Fraternal)
• Identical 100 genetic similarity
• Fraternal 50 genetic similarity

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Behavioral Genetics

• Heritability Proportions of variance due to
  variations in genotypes

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Behavioral Genetics

• 2. Adoption Studies
• 3. Family Studies
• E.G. Schizophrenia

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Non-shared Environment

• Unique environment in which each child (even in
  the same family) lives
• Unique parent-child interaction
• Different school experiences
• Different peer group