The original build for Mass Effect's Commander Shepard was originally developed as a woman. The intention was always for Commander Shepard to be both female and male, but the very first test animation for Mass Effect used a female model. For all intensive purposes, the first steps that the Commander ever took in Mass Effect were made by FemShep.
Why the gender of the model matters, I don't know. Naughty Dog Developer Jonathon Cooper revealed this information via Twitter:
Ten years ago this month, my very first anim test for Mass Effect. Yup, Commander Shepard was originally a woman: pic.twitter.com/FhC2E0FSrA
— Jonathan Cooper (@GameAnim) January 9, 2015
Cooper went on to include another clip of an original test animation and verified the intention of having Shep available as both sexes:
For those asking, I repurposed mocap from Jade Empire. Shepard was always planned to be both male & female after JE's pre-set characters.
— Jonathan Cooper (@GameAnim) January 9, 2015
So, there's that. It's interesting to see the first animation test.
[Twitter]