“…Research on gamete donors can be categorized according to the relation between the donor and the recipient/offspring into: [1] known or personal donors who donate to a couple known to them or are recruited by an infertile couple (7,8), [2] anonymous donors (9)(10)(11)(12)(13)(14)(15), [3] donors who donated anonymously but later actively made themselves identifiable to the offspring, for example, through a voluntary contact register such as the Donor Sibling Registry (DSR) (16,17), and [4] identifiable donors who chose to donate through identity-release arrangements despite the option to donate anonymously (18) or who donate under identity-release jurisdictions (19)(20)(21)(22)(23)(24). Studies have investigated donors' demographic characteristics (9,15,25), motives for donation (9, 12, 14-18, 20, 23, 25), attitudes toward anonymity/information-sharing (9,12,15,18), and views concerning the offspring (9,14).…”