Wize University Psychology Textbook > Genetics & Evolution
Twin & Adoption Studies
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Twin and Adoption Studies
To study genetic and environmental influences on intelligence and other traits, we use twin and adoption studies
- Siblings share 50% of their DNA
- Fraternal (dizygotic) twins develop from two different eggs fertilized by two different sperm cells, and also share 50% of their DNA
- Identical (monozygotic) twins develop from one egg fertilized by one sperm cell and share 100% of their DNA
Twin studies compare identical twins with fraternal twins and non-twin siblings to understand the influence of genetics
Adoption studies compare twins raised together with twins raised apart to understand the influence of environment
Even in twins raised together, the environment is not 100% identical
- Shared environment - nutrition, household income, etc.
- Non-shared environment - friends, teachers, etc.
Mark Yourself Question
- Grab a piece of paper and try this problem yourself.
- When you're done, check the "I have answered this question" box below.
- View the solution and report whether you got it right or wrong.
Practice: Twin & Adoption Studies
Can family and twin studies be used to determine whether a trait is genetically transmitted? Why or why not?