Heritability of attitudes toward gay rights is estimated at 0.3 to 0.5, slightly higher than the heritability of homosexuality.

Judge against the behavioural-genetics literature available as of 2014-09-30. Both parts must hold: (a) twin or family studies estimate the heritability of attitudes toward gay rights or homosexuality at roughly 0.3 to 0.5, and (b) heritability estimates for homosexuality or same-sex orientation itself are at or a little below that level. True: both parts are supported by published estimates. Mostly true: both hold in substance with a minor numeric slip (for example, attitude estimates of about 0.25 to 0.55, or homosexuality estimates about equal to attitude estimates rather than clearly lower). Mixed: one part is well supported and the other is not. Mostly false: the figures exist only in a single narrow study or a different measure (such as general social conservatism rather than gay-rights attitudes) and are presented as general, or the comparison is reversed by a small margin. False: published estimates for gay-rights attitudes lie well outside 0.3 to 0.5, or homosexuality is clearly shown to be substantially more heritable than such attitudes.

Set before the research began.

1. E1 Etiology of male sexual orientation in an Australian twin sample Psychology, Evolution & Gender (Kirk, Bailey, Martin) · December 2000

   “attitude to homosexual sex, number of male and female sexual partners), with approximately 42 to 60 per cent of observed variance estimated to be due to genetic influences in these variables.”

2. E2 Measurement models for sexual orientation in a community twin sample PubMed (Behavior Genetics, Kirk KM, Bailey JM, Dunne MP, Martin NG) · July 2000

   “Estimates of the heritability of homosexuality in this sample ranged between 50 and 60% in females but were significantly lower (heritability of approximately 30%) in males.”

3. E3 Genetic and Environmental Effects on Same-sex Sexual Behavior: A Population Study of Twins in Sweden Archives of Sexual Behavior (Långström, Rahman, Carlström et al.) · 2010

   “Biometric modeling revealed that, in men, genetic effects explained .34–.39 of the variance, the shared environment .00, and the individual-specific environment .61–.66 of the variance.”

4. E4 Transmission of Attitudes Toward Abortion and Gay Rights: Effects of Genes, Social Learning and Mate Selection Behavior Genetics (Eaves, Hatemi) · 29 March 2008

   “Results are consistent with a substantial role of genetic liability in the transmission of both attitudes.”

E1, an Australian twin study, reports that about 42 to 60 per cent of variance is genetic across a set of measures that includes attitude to homosexual sex. That roughly matches 0.3 to 0.5 but runs a little higher, and the figure is pooled across several measures. E4 finds a substantial genetic role in gay-rights attitudes but gives no number in the quoted text. For homosexuality itself, E2 gives about 30% heritability in men (50 to 60% in women), and E3 gives .34 to .39 in men [E2][E3]. So same-sex orientation is mostly at or below the attitude figures, though the Australian female estimate is about equal to or above them. Both parts hold in substance, with some numeric imprecision.