To answer OP's question, I think they look angry because the eyebrows slant inward (like I think it's the only eyebrow option for the males)

Quote Originally Posted by Elmeron View Post
I wanna keep it non-adult but... HOW?! How does that even work... The pain... Good god. And imagine if they had a male baby vs. a female one? The male babies must be scary.
On that note, are the babies born with horns? Ouch. imagine the contractions on that thing. Gives a whole new meaning to the phrase "it's crowning"