Just to add a useful, encouraging data point. My DBA supervisor has a really challenging stammer, and he's fantastic -- both as a technical leader and a people

Just to add a useful, encouraging data point. My DBA supervisor has a really challenging stammer, and he's fantastic -- both as a technical leader and a people manager. We value him highly and his stammer has never, ever been a problem (or changed the way people interact with him). There is hope!