Why such a point of characters' birthdays?

[huntergreen_3]

No: HPFGUIDX 110975

Caspen
>> if you don't think that "they're picked as randomly
as all that, ...," why, and how do you think they are picked? Given
the amount of time and attention that other seemingly (to some)
trivial details get here (someone posted a whole theory at least
involving, if not based upon, Hermione's announced, whether random
or not, birthday here, not too long ago), what are we to make, if
anything of this latest announcement of Percy's birthday (Happy
Birthday Percy, despite your recent flirtations with the dark side,
or at least ignorance! Yay!)?<<

HunterGreen:
She could have come up with the birthdays a long time ago when she 
originally created the characters, it just never was important enough 
to mention before. In the case of Hermione and the twins, for 
example, there has been times in the text of the books that their 
birthdays are mentioned (Hermione's in PoA and Fred & George's in 
GoF), which would suggest that she had come up with at least some of 
the birthdays beforehand. 
Its not an uncommon thing for authors to come up with all of the 
information about their important characters, even the information 
that isn't important (like birthdays and middle names). Including 
that on the website is just for fun, it has no bearing on anything.