User blog comment:The Milkman/The Shepard Fan Club/@comment-1388547-20120720194923

I think part of the relative lack of personality is that Shepard is supposed to be an empty vessel into which the player pours his or her own concept of the character. There is rather a lack of humor on Shep's part over the course of the series, but the Paragon/Renegade split does a decent job of nice/mean characterization, and you can sort of emote a bit in the dialog options.

I agree about the lack of back story references (Sole Survivor in particular, but maybe also the others) after ME1. Yes, Shepard should have been able to make an extra comment about fighting a Thresher Maw on foot -- dread, or desire for revenge -- if the Commander is a Sole Survivor. Some comments about the criminal underworld in a few places might have been good for an Earthborn Shep, given that Earthborn ran with a gang once, and maybe a Spacer should be able to chat with the quarians a bit about shipboard life in the Alliance Navy as compared to the Migrant Fleet. I'm not too bothered by this, though; it would have been nice not to see this fall by the wayside, but I never paid it much attention until you pointed it out.

The thing that bugged me was how the writers gave Shepard characterization in Mass Effect 3 that was independent of what the player wanted to give. Your example of Shepard being torn up about the Reaper occupation of Earth is a good one. All but one of my ME3 characters are not from Earth, and my one Earthborn does not have good memories of the planet, and would not mind seeing the slum where she grew up burned to the ground. Another example is the dream sequences, which show Shepard preoccupied with something that I, the player, don't really care about. I'm almost inclined to put these down to the Reapers messing with Shepard's mind -- not to the level of the Indoctrination Theory, but surely with all the exposure to Reapers and their artifacts Shep has had, the Commander must be getting somewhat tainted by them.