Part of the gripe I have is that someone may think one person is older but it's actually the other way around. They either go by looking at the two actors and guessing who is older or if they are correct someone reading may not know which one is older. It gets confusing.

Take Atlantis' JF and DH. When the series first started a lot of people thought DH was older, but JF is about a year and a half older.