All this raises a question - which modern RPG ever does something with gender options? Numenera adds a quest for female PC, but what others do?
From the top of my head:
Lionheart: Legacy of the Crusader has a part that if you play as a female Shakespeare flirts with you and gives you a unique ring. Although that game is 14 years old.
There is
Fallout 2 of course, where females can screw a few characters for some benefits, can get raped by Myron (depending on SPECIAL values), will have a hard time to fight in boxing matches, they can can marry Miria or Davin (males can only marry Miria). Males can screw Angela, date Phyllis and can also donate sperm.
Both
Fallout 3 and
New Vegas have specific things dependent of gender (some examples: Flirting with Mr Burke, convince the guy who wants to bone Sierra (the crazy nuka cola girl) to go to the Nuka factory so he can have a threesome, females can't fight in Legion arena, sleep with Benny, etc).
Morrowind has some differences if you play a female (Nels Llendo encounter, Mistress Dratha hates men, etc).
Oblivion has gender alter the starting attributes (for example Khajiit males lose 10 Endurance while females lose 10 Strength).
Arcanum of Steamworks and Magick Obscura also has some differences between male and female character. Male Characters have no bonuses or penalties while female ones have a penalty on strength but have a bonus on Constitution. Female characters have access to the clothes that make people like them more (Elegant Dress) at the starting "store" while males can only buy those clothes (Smoking Jacket) later in the game. Also females do not have access to some races (Dwarves, Gnomes, Halflings, and Half-Ogres). I can't remember but I think there might be some dialogue and maybe a quest or two that are different if the main character is a female.
Harvest Moon Boy & Girl you can make offerings to some goddess and if you’re male you get a red power berry (which increases your stamina), if you're female, you get a piece of lumber worth 3000G. You can later get the same reward as the opposite gender but the initial order is different.
Harvest Moon 3 has some differences between playing a male or female character. Females start with a free cow and a brush, but cannot upgrade tools, while the male character can. Males have more stamina than the female. When the female character gets married the game ends, but the male character can continue the game after marriage.
I am old so I have no idea what games should be considered "modern". Also since I have been broke for many years, I haven't played more recent games (since they are expensive).