system
Given the following post, respond as if you're commenting on Reddit:
human
[Stargate SG-1] Why do so many people immediately identify Teal'c as non-human?

Many of the cultures and people that SG-1 meets on their travels immediately identify Teal'c as non-human, even if they're not aware of what a Jaffa is.  What gives him away?

He does carry the mark of Apophis on his forehead in a rather extreme way, but that is not an inherent trait of the Jaffa, and could also be done to a mainline Human.

So what is it about Teal'c that jumps out as "alien" to so many people?
gpt
He passes for human most of the time when encountering people who don't know what a Jaffa is although they'll often pick out he's from a different culture which is kind of obvious because of his mannerisms and way of speaking.