She is one of my prettier babies! (missing ear and all)...
And yes, it's also a distinct possibility that her ear was a casualty of birth rather than a genetic anomaly. I understand that to be a possibiliity but that doesn't keep me from trying to see if I can duplicate the look.
I've had mice end up with weird "subtractions"...
One day I was cleaning mouse cages and I noticed that a male mouse looked kind of funny... on closer examination I realized that one of his legs was GONE... and I couldn't even find a scabbed over area for the stump! He lived for three more months before it was his turn to be snake food. Actually had a rash of Mice-Suddenly-Misplacing-Limbs. Had one mouse, in a newly cleaned cage, I checked the day after cage cleaning, bedding still pretty and new-looking...only the mouse has lost a leg, and has no scab and there's no blood on the bedding and no shriveled up leg in the bedding!
Had another mouse who's tail died.... it was really ICKY and me and my step daughter decided to cut it off with scissors. (yes, we did!) SNIP! no complaint from the mouse... no blood. Just a dead tail.
Anyway, this ear doesn't look like a mutilated remnant, but can't tell because I lost my CSI kit.