When examining the rates of homosexuality between identical twins and fraternal twins or non-twin siblings, the following has been reported by research: if one identical twin is gay, his brother has a ________% chance of being gay as well. If a fraternal twin is gay, his brother has a ________% chance of being gay as well.

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Research has shown that if one identical twin is gay, the other twin has a 52% chance of also being gay, while if a fraternal twin is gay, the chance that his brother is also gay is only 22%. This suggests a strong genetic component to sexual orientation, as identical twins share all of their genes while fraternal twins only share about 50%.

When Examining the Rates of Homosexuality Between Identical Twins and Fraternal