Why such a point of characters' birthdays?

[Justine]

No: HPFGUIDX 111102

Stef:
Like I signed my other post...we won't actually know what's going on 
> until either a person we canonically know as dead is celebrated or 
> someone who's birthday we know doesn't show up. As of now, we know:
> Fred - April 1
> George - April 1
> Neville - July 30
> Harry - July 31
> Ginny - August 11
> Percy - August 21
> Angelina - The week after Hallowe'en (GoF 16)

Justine:
Darnit.  The first news article on the site was from March 15th, and 
the twins' birthday, noted as April 1st on the site, was missed.  
Say it ain't so, Jo!

Justine