It does neither because sex and gender are a social construction... 
The gender one I have heard before, but never sex. Who seriously believes biology is a social construct?
Judith Butler.
I haven't read her, but I have a hard time believing that she literally thinks that our genitals are formed one way or another by society. Mostly because that's patently absurd. Can't seem to find a definitve quote either, just people talking about her work.
Well, you'd be surprised what some feminists actually believe. That said, it is not necessarily a matter of biological facts like men have a penis and women have a vagina, but also the social and cultural context in which it is viewed.
If you want an actual quote from Butler here you are:
If the immutable character of sex is contested, perhaps this construct called ‘sex’ is as culturally constructed as gender; indeed, perhaps it was always already gender, with the consequence that the distinction between sex and gender turns out to be no distinction at all.(Butler 1999, 10–11)
A more broader view of sex and gender in feminism:
Many people, including many feminists, have ordinarily taken sex ascriptions to be solely a matter of biology with no social or cultural dimension. It is commonplace to think that there are only two sexes and that biological sex classifications are utterly unproblematic. By contrast, some feminists have argued that sex classifications are not unproblematic and that they are not solely a matter of biology. In order to make sense of this, it is helpful to distinguish object- and idea-construction (see Haslanger 2003b for more): social forces can be said to construct certain kinds of objects (e.g. sexed bodies or gendered individuals) and certain kinds of ideas (e.g. sex or gender concepts). First, take the object-construction of sexed bodies. Secondary sex characteristics, or the physiological and biological features commonly associated with males and females, are affected by social practices. In some societies, females' lower social status has meant that they have been fed less and so, the lack of nutrition has had the effect of making them smaller in size (Jaggar 1983, 37). Uniformity in muscular shape, size and strength within sex categories is not caused entirely by biological factors, but depends heavily on exercise opportunities: if males and females were allowed the same exercise opportunities and equal encouragement to exercise, it is thought that bodily dimorphism would diminish (Fausto-Sterling 1993a, 218). A number of medical phenomena involving bones (like osteoporosis) have social causes directly related to expectations about gender, women's diet and their exercise opportunities (Fausto-Sterling 2005). These examples suggest that physiological features thought to be sex-specific traits not affected by social and cultural factors are, after all, to some extent products of social conditioning. Social conditioning, then, shapes our biology.
Second, take the idea-construction of sex concepts. Our concept of sex is said to be a product of social forces in the sense that what counts as sex is shaped by social meanings. Standardly, those with XX-chromosomes, ovaries that produce large egg cells, female genitalia, a relatively high proportion of ‘female’ hormones, and other secondary sex characteristics (relatively small body size, less body hair) count as biologically female. Those with XY-chromosomes, testes that produce small sperm cells, male genitalia, a relatively high proportion of ‘male’ hormones and other secondary sex traits (relatively large body size, significant amounts of body hair) count as male. This understanding is fairly recent. The prevalent scientific view from Ancient Greeks until the late 18th century, did not consider female and male sexes to be distinct categories with specific traits; instead, a ‘one-sex model’ held that males and females were members of the same sex category. Females' genitals were thought to be the same as males' but simply directed inside the body; ovaries and testes (for instance) were referred to by the same term and whether the term referred to the former or the latter was made clear by the context (Laqueur 1990, 4). It was not until the late 1700s that scientists began to think of female and male anatomies as radically different moving away from the ‘one-sex model’ of a single sex spectrum to the (nowadays prevalent) ‘two-sex model’ of sexual dimorphism. (For an alternative view, see King 2013.)
Fausto-Sterling has argued that this ‘two-sex model’ isn't straightforward either (1993b; 2000a; 2000b). She estimates that 1.7% of population fail to neatly fall within the usual sex classifications possessing various combinations of different sex characteristics (Fausto-Sterling 2000a, 20). In her earlier work, she claimed that intersexed individuals make up (at least) three further sex classes: ‘herms’ who possess one testis and one ovary; ‘merms’ who possess testes, some aspects of female genitalia but no ovaries; and ‘ferms’ who have ovaries, some aspects of male genitalia but no testes (Fausto-Sterling 1993b, 21). (In her [2000a], Fausto-Sterling notes that these labels were put forward tongue–in–cheek.) Recognition of intersexes suggests that feminists (and society at large) are wrong to think that humans are either female or male.
To illustrate further the idea-construction of sex, consider the case of the athlete Maria Patiño. Patiño has female genitalia, has always considered herself to be female and was considered so by others. However, she was discovered to have XY chromosomes and was barred from competing in women's sports (Fausto-Sterling 2000b, 1–3). Patiño's genitalia were at odds with her chromosomes and the latter were taken to determine her sex. Patiño successfully fought to be recognised as a female athlete arguing that her chromosomes alone were not sufficient to not make her female. Intersexes, like Patiño, illustrate that our understandings of sex differ and suggest that there is no immediately obvious way to settle what sex amounts to purely biologically or scientifically. Deciding what sex is involves evaluative judgements that are influenced by social factors.
Insofar as our cultural conceptions affect our understandings of sex, feminists must be much more careful about sex classifications and rethink what sex amounts to (Stone 2007, chapter 1). More specifically, intersexed people illustrate that sex traits associated with females and males need not always go together and that individuals can have some mixture of these traits. This suggest to Stone that sex is a cluster concept: it is sufficient to satisfy enough of the sex features that tend to cluster together in order to count as being of a particular sex. But, one need not satisfy all of those features or some arbitrarily chosen supposedly necessary sex feature, like chromosomes (Stone 2007, 44). This makes sex a matter of degree and sex classifications should take place on a spectrum: one can be more or less female/male but there is no sharp distinction between the two. Further, intersexes (along with trans people) are located at the centre of the sex spectrum and in many cases their sex will be indeterminate (Stone 2007).
More recently, Ayala and Vasilyeva (2015) have argued for an inclusive and extended conception of sex: just as certain tools can be seen to extend our minds beyond the limits of our brains (e.g. white canes), other tools (like dildos) can extend our sex beyond our bodily boundaries. This view aims to motivate the idea that what counts as sex should not be determined by looking inwards at genitalia or other anatomical features.
Also:
This is a good site to get a general view on feminist ideas and many other ideas from different fields.
https://plato.stanford.edu/entries/feminism-gender/
