Toady One speak (briefly) about trans people in #dwarffortress. Although trans people are not really included in the game, the dev explains that the gender of a dwarf is stored in the body, and in the soul, which could make people with different genders in the soul and body.
I wonder whether these genders are limited to male/female or could be made nonbinary. (http://dwarffortresswiki.org/index.php/DF2014:Gender suggests it could be possible)
Oh and http://www.bay12forums.com/smf/index.php?topic=144445.0 suggests sexual orientation isn't limited to heterosexuality.
http://www.bay12forums.com/smf/index.php?topic=159164.msg7606864#msg7606864