You know, there was another RPG - one with fully voiced NPCs even - which also had player character origin stories as one of its major selling points and managed to handle full character customisation (given name, sex, and when appropriate also race) within those Origins just fine almost a decade ago...
How many dialogues, quests and NPC relationships were dependent on the origins?
I'm not arguing that it can't be done. Either there are restrictions on how it is done, or it is 10 times the work doing it in all possible combinations of race and gender.