Chapter 5 - 'Twin Studies And Adoption Studies'

Question 1

State the difference between identical and non identical twins.

Answer 1

Monozygotic (or identical) are formed when a single egg splits into two. They share 100% of their genes.

Dizygotic (or fraternal) twins develop when the female produces two separate eggs fertilised by two different sperm cells. They share 50% of genes.

Question 2

List why researchers use twin adoption studies to test the effects of environment on development.

Answer 2

Strictly controlled genetic variable.
Valid and reliable.
Ethical.

Question 3

Both monozygotic and dizygotic twins were tested over time throughout childhood.

Explain the results documented.

State what this led to believe.

Answer 3

Monozygotic twins were very similar to one another in intelligence, showing both the same strength and weaknesses.

Dizygotic twins were also similar though less than monozygotic twins.

That intelligence is partly determined from heredity.

Question 4

Monozygotic and dizygotic twins were tested on personalities.

Explain what was tested and give the results.

Answer 4

Extroversion (outgoingness) and neuroticism (emotional instability). It was discovered that monozygotic living together were more alike than dizygotic twins.