Neville's family

[meriaugust]

No: HPFGUIDX 87407

I was just rereading my copy of SS (I am on vacation now and can 
thankfully read whatewver I want!) and I came across this line in 
the Sorting Hat chapeter, page 125, American edition where all the 
new Gryffindors are talking about their families. "Well, my gran 
brought me up, and she's a witch," said Neville, "but the family 
thought I was all Muggle for ages." Neville then goes on to describe 
the Blackpool Pier incident and how he almost drowned. My question 
is this: why would the Longbottoms think that Neville was all 
Muggle? Was his mother from a Muggle family? Or are the Longbottoms 
not all wizards and witches as I thought? I always assumed that the 
Longbottoms were an old wizarding family (ala the Weaslys and the 
Malfoys) but maybe Gran and Frank were the only ones to have any 
magical powers. Maybe that's why the majority of the Longbottom 
family emerged unscathed from the first war: they weren't magical 
enough for LV to care about killing them. Any thoughts? 
Meri