Which Frog brother is older?

[prepare4trouble]

I've seen it both ways in fic. I can't decide which is better. I've always written Edgar as the older brother, just because he appears to be in charge, and he's Head Frog. But I've seen some where Alan is older, but Edgar's personality places him in the leader role even though he's the younger sibling. I think I like it that way, actually. It adds a new layer of depth to the characters.