In Ancient Greece, male nudes were a common occurrence in classical statues, while depictions of women were often covered, sometimes just partially to cover genitalia (Good examples: https://imgur.com/J7GPPnW, https://imgur.com/8JH47mR). In fact, some scholars believe that depictions of Venus/Aphrodite is one of the main reasons for so many statues of semi to fully nude women to begin with^(1). Aphrodite of Knidos (https://imgur.com/a/pEXhTAq) is one of the most famous depictions of the goddess around 350 BC. This statue is often considered the first three dimensional fully nude female form^(2) and is a departure from korai, ancient sculptures of women which were commonly depicted with wearing a chiton, peplos, and himaton^(3) (https://imgur.com/a/Qhqqhj2). Praxiteles' sculpture introduced more varied depictions of women (albeit these nude sculptures were almost always goddesses or mythical characters, never real women).
Why were real women never depicted and furthermore, why not genitals? The Ancient Greeks prided themselves on being civilized, shocked by other civilizations whose feelings about women's roles in society and depictions of them differed^(1). Greek culture placed on emphasis on women being in the home, running the day to day operations of a home and raising a family^(4). To be a woman of good standing in Athens and be depicted as a nude statue would have been scandalous^(1). Female genitals reflected the cultural modesty of the day, with the word aidoia being used to describe them, which translates to 'shameful parts'^(1). While there was this duality between female nudity that was acceptable and unacceptable, there is a consistent absence of genitalia for women in statues, which I might infer to be the last barrier for all depictions of the female form, reflecting on cultural attitudes of female modesty.
1: Schriemer, Lydia. “Undressing the Female Nude: The Paradox of Morality in Ancient Greek Sculpture.”
2: Higgs, Peter. “Review: The Aphrodite of Knidos and Her Successors. A Historical Review of the Female Nude in Greek Art.” The Journal of Hellenic Studies, vol. 117, 1 Jan. 1997, p. 262.
3: Witcombe, Christopher. "Kore Statues." http://arthistoryresources.net/greek-art-archaeology-2016/archaic-kore-sculpture.html
4: Meyer, Jørgen Christian. "Women in Classical Athens in the Shadow of North-west Europe or in the Light from Istanbul."