Bailey and Pillard

Question 1

Year

Answer 1

1990

Question 2

Aim

Answer 2

Investigate the role genetics may play in sexuality.

Question 3

Sample

Answer 3

MZ and DZ twins, adoptive brothers.
All male volunteers, raised together.

Question 4

Procedure

Answer 4

Sexual orientation of relatives found out by either asking relative or participant.

Participants given questionnaire
- Assess level of CGN (childhood gender non-conformity, meaning they did not conform to gender-related patterns, identified with opposite gender)
- clothing, toys, playmates, identification with characters.

Question 5

Results and conclusion

Answer 5

Both homosexual:
- 52% of MZ
- 22% of DZ
- 11% of non-related adopted brothers

CGN did not predict homosexuality, not correlated.

More closely genetically linked means that they are more likely to have the same sexual orientation.