Mass Effect has two leads, Mark Meer and Jennifer Hale, but you’ll only hear one of them as Commander Shepard per playthrough. According to player stats, most people play as a guy, meaning Mark Meer is their Shepard throughout the trilogy.
However, Meer encourages players to give FemShep a go - purely so they can enjoy the performance of his co-star, Hale. Speaking with PC Gamer, Meer says that he’s a huge fan of her work, and doesn’t have any problem with players choosing to only play as FemShep because of her performance.
For the record… if your shep isn’t occasionally an asshole…. You’re playing it wrong.
(Like on the starter mission, knocking out the researcher. Or the fanboi on citadel.)