Why such a point of characters' birthdays?

[lilypo2007]

No: HPFGUIDX 110978


Caspen:

> > What, for instance, is the point of telling us that today is
> > Percy's birthday? 

 
Lilyp
I think there are some information linked to the birthdays. For
instance, now we know that Percy was 17 just a week before going back
to  Hogwarts to his seventh year there. That's why he couldn't have
his apparation exam and had to wait the next summer. The twins were 17
in April and had the whole month of July to prepare for the exam and do
it. They were able to apparate before going back to Hogwarts. 

That means Ron will probably be able to apparate at the beginning of
book seven. Harry as well. But Hermione will not, because she will be
17 only on Sept 19th. 

That also mean Ron will be of age in the end of Hp and the HBP, Harry
will be of age only at the beginning of book seven and Ginny will be
of age only after the trio leaves Hogwarts.