Goblins have a species survival trait which allows them to selectively change their gender, allowing for repopulation in the wake of the destruction of a tribe.
A goblin enters a trance like state for 24 hours minus their Constitution Score. During this time their body undergoes a complete transformation to the selected gender. This gender is not limited to a male/female binary and may be anywhere on a spectrum between these two points.
Once this change has been made a goblin cannot undergo another change for one week.
Many goblins choose not to choose and the majority of goblins are born without any specific sexual characteristics. Depending on the culture and traditions of their tribe they may choose, or be assigned a gender when they reach adulthood.
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