Harry's Grandparents

[Marcie]

No: HPFGUIDX 79663

This is a question that has been bugging me for some time now. 
Throughout all the books, there has been very little mention of 
Harry's grandparents from either side of the family. Petunia Dursley 
bitterly mentioned to Harry her parents' elation when Lily got 
accepted into Hogwarts in the first book, and in TOOTP, Sirius 
reminisced how he was often over at the Potter's home for dinners and 
how James' father joked that he might as well adopt Sirius as the 
latter was always spending time there to get away from the Black 
family. What happened to them? There must be some significance to the 
Potter family in the Wizarding world. James, at the very least, must 
have had a pureblood parent who married a Muggle (this is just pure 
speculation) or had pureblood parents who were like the Weasleys and 
associated with Muggles. There is no mention that these parents were 
dead or killed by Voldemort. Lily must also have some Wizarding 
family somewhere in her ancestry, and I am assuming that Petunia has 
some magical abilities, too, but is more or less a Squib. It is 
understandable, too, that Petunia would estrange herself from her 
parents (if they were alive by the time Harry and Dudley were born) 
because she felt that they always favoured Lily, anyway. The way I 
look at it, James' parents would be in their 60s by the time Harry 
came to his adolescent years. Lily and James could have been married 
in their late teens or early 20s, and James' parents would have been 
in their 40s during that time. I'm curious to know if J.K. Rowling 
will expand further on Harry's ancestry, as she did with Sirius 
Black's family tree. Any speculation from anyone or ideas would be 
greatly appreciated. I understand that this query might have been 
touched on already but would like to know what else anybody thinks. 
Thanks.