[quote=@Retired]
Why is Babs older than Harley?
[/quote]

I have no clue. Though it's always been kind of a thing that Harleen became a doctor at Arkham at a young age and right out of college, so... maybe? Eh, even that's a stretch. I feel like those ages should be reversed, if anything. If not marking Babs' age down to a 21-22 at peak Batgirl.