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Twin Studies and Adoption Studies

Twin Studies and Adoption Studies. I get it from my parents. XYY. Biology Genetics Social Behavior. Environment. Genetic predisposition and never commit a criminal act Lack of a genetic predisposition and be a criminal.

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Twin Studies and Adoption Studies

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  1. Twin Studies and Adoption Studies I get it from my parents

  2. XYY • Biology • Genetics • Social Behavior

  3. Environment • Genetic predisposition and never commit a criminal act • Lack of a genetic predisposition and be a criminal

  4. How Can we Determine the Extent of Criminal Behavior is Genetically Influenced? • TWIN STUDIES • ADOPTION STUDIES

  5. Twins • Monozygotic Twins • Single Egg • Dizygotic Twins • Separate Eggs • Share about half the genes

  6. Johannes Lange(1920’s) • 30 Pairs of Same sex twins • 13 Identical 17 Fraternal Pairs • One Member of Each Pair was a known criminal

  7. Twin Studies Result ( Lange 1920) • 13 Identical Twins • 10 Pairs: Both Twins Were Criminal

  8. Twin Studies Result ( Lange 1920) • 17 Pairs of Fraternal Twins • 2 Pairs Were Criminal

  9. Karl Christianson and Sarnoff A. Mednick 1881-1910 Study • 3586 pairs of twins • Listed Serious Offenses only

  10. Mednick and Christiansen • Identical Twins: If one is criminal, the other is likely to be criminal by 50% • Fraternal Twins: If one criminal and the same sex as the other, the other has a 20% likelihood of being criminal.

  11. David C. Rowe, D. Wayne Osgood • Recent American Study • Supported the Findings of Christiansen and Mednick

  12. Adoption Studies • Best way to separate the Inherited Traits from Environmental Conditions • Largest Study was in Denmark 1924-1927 by Sarnoff A. Mednick • 14,427 Male and Female Adoptions • Felony Cases Only

  13. If the Biological Parents were not Criminal and the Adoptive Parents Were not Criminal, What Percent of the Offspring were Criminal?

  14. 13.5% Criminal

  15. If the Adoptive Parents were Criminal and the Biological Parents were not Criminal?

  16. 14.7 % Criminal

  17. If the Adoptive Parents were Non Criminal and the Biological Parents were Criminal?

  18. 20 % Crime Conviction of the Offspring

  19. How About Both Sets of Parents Criminal?

  20. 24.5%

  21. Does this Data Suggest that Criminality is Inherited?

  22. How About Females? • Study of 862 Adopted Males • 913 Adopted Females

  23. Who Do You Think Gets More Criminal Tendencies Biologically: Males or Females?

  24. Studies Show that Females Inherit Criminal Tendencies More than Males

  25. Are Violent Tendencies Inherited? • No one has ever found evidence of inheritance of violence. • Mednick

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