This has been reported in multiple news media recently:
It's also interesting what is said about the identical twin study: Sexual orientation can't be explained by genetics since it turns out a pair of identical twins (who share all their genes) can have different sexual orientations.
More: Length of ring and index fingers 'linked to sexuality' (17. Oct. 2018)Women whose left index and ring fingers are different lengths are more likely to be lesbians, a study suggests.
It's also interesting what is said about the identical twin study: Sexual orientation can't be explained by genetics since it turns out a pair of identical twins (who share all their genes) can have different sexual orientations.