I looked up “gender” in the Oxford English Dictionary, and found these two — 3a & 3b — which are relevant (the others are about the use of gender in language and electronics.) Note the phrase “originally extended from the grammatical use” which I find interesting, and that the 3b usage it cited as coming from the US, and aligns with Heying’s definition I quoted above.
3a. gen. Males or females viewed as a group; =
sex n.1 1. Also: the property or fact of belonging to one of these groups.
Originally extended from the grammatical use at sense 1 (sometimes humorously), as also in Anglo-Norman and Old French. In the 20th cent., as sex came increasingly to mean sexual intercourse (see
sex n.1 4b), gender began to replace it (in early use euphemistically) as the usual word for the biological grouping of males and females. It is now often merged with or coloured by sense 3b.
Quotations:
1474 in C. L. Kingsford Stonor Lett. & Papers (1919) I. 142 (MED) His heyres of the masculine gender of his body lawfully begoten.
a1500 (▸a1460) Towneley Plays (1994) I. xxx. 408 Has thou oght writen there Of the femynyn gendere?
1580 W. Fulke Retentiue 92 For there is but one Lord..both of men and of Angels, which doth not onely exclude all other Lordes of the masculine gender, but much more all Ladyes.
1632 S. Marmion Hollands Leaguer iii. iv. sig. g4v Here's a woman: The soule of Hercules has got into her. She has a spirit, is more masculine, Then the first gender.
1656 Earl of Monmouth tr. T. Boccalini Ragguagli di Parnasso 135 Strength..was a vertue attributed to the masculine gender.
1719 J. Harris Astron. Dialogues 141 I think the Poets make her change her Sex, and turn He-Thing, as if she could not be as useful when of our Gender, as of yours.
1723 Lady M. W. Montagu Let. 7 Dec. (1966) II. 33 Of the fair Sex..my only Consolation for being of that Gender has been the assurance it gave me of never being marry'd to any one amongst them.
1818 T. H. Bayly Parl. Lett. 32 The women adore you, and call you defender, And friend to the rights of the feminine gender.
1868 Radical 3 386 A very modest lady acquaintance of ours can bake bread, shoot a gun, ride a horse... Yet she is not an exception to the radical capacity of her gender.
1896 Daily News 17 July 6/4 As to one's success in the work one does, surely that is not a question of gender either.
1936 Mademoiselle Mar. 43/1 I find I belong to the wrong gender to take part in such confabulations.
1970 Sunday Times 29 Nov. 29/2 Adolescents of both genders strode along..with books and long flaxen unisexual hair.
2009 Daily Record (Glasgow) (Nexis) 21 Oct. 35 While the majority of paedophiles are male, there is a substantial minority who are women. But whatever their gender there is no excuse for their behaviour.
3b. Psychology and Sociology (originally U.S.). The state of being male or female as expressed by social or cultural distinctions and differences, rather than biological ones; the collective attributes or traits associated with a particular sex, or determined as a result of one's sex. Also: a (male or female) group characterized in this way.
Quotations:
1945 Amer. Jrnl. Psychol. 58 228 In the grade-school years, too, gender (which is the socialized obverse of sex) is a fixed line of demarkation, the qualifying terms being ‘feminine’ and ‘masculine’.
1950 Amer. Jrnl. Psychol. 63 312 It [sc. Margaret Mead's Male and Female] informs the reader upon ‘gender’ as well as upon ‘sex’, upon masculine and feminine rôles as well as upon male and female and their reproductive functions.
1968 Life 21 June 89 When the separation of fashions according to gender began to vanish, retailers discovered a bonanza.
1978 D. Pearce in Urban & Social Change Rev. 11 i–ii. 35/1 The major implication for policy of both the feminization of poverty and the..labor-force participation of welfare mothers is that gender cannot be ignored.
1981 Heresies No. 12. 67/3 Our ideology and practice of sex roles construct..two mutually exclusive categories, that is, genders.
2007 New Yorker 6 Aug. 13/2 There's no breaking news here—identity and gender have been on the contemporary-art docket for years.