If I had the resources, I’d answer everyone’s questions with science.

Question: Is homosexuality genetic?
Hypothesis: Homosexuality will be passed on more frequently by two homosexual parents than two heterosexual parents.

Procedure

1. Collect sperm samples from 110 homosexual males and 110 heterosexual males.
2. Screen families seeking children, eliminating those which exhibit negative feelings toward homosexuals or heterosexuals, and those from environments which would promote or demote either hetero- or homosexuality.
3. Artificially inseminate 110 homosexual females from the screened families with the homosexual males’ sperm.
4. Artificially inseminate 110 heterosexual females from the screened families with the heterosexual males’ sperm. 
5. After each of the resulting children turns 21, survey each child to evaluate their self-described sexuality/gender identity.
6. Record results.
7. Take note of other environmental factors. (If the hypothesis proves false, a different one could still be true based on this research.)

Data

Children From Homosexual Parents
[Description of Gender Identity] [Description of Sexuality] [Description of Environmental Factors and Experiences]

Children From Heterosexual Parents
[Description of Gender Identity] [Description of Sexuality] [Description of Environmental Factors and Experiences]

I’m no scientist; this is amateurish as best. Major issues with this experiment would be

• Trying to find families willing to participate in this experiment.
• Avoiding having the resulting children be upset at their unwilling participation in the experiment.
• Avoiding general controversy amongst the scientific community/ general populace.
• Funding.
• Time.
• High margin of error based on environmental factors.