The author has indeed drawn inspiration from The War of the Roses.
He mentioned that in correspondence with a fan. From Citadel SSM Entry "Historical Influences":
Most of my borrowings, however, come from English and French medieval
history, simply because I am more familiar with those than with the heroes, legends, and traditions of other countries. The Wars of the
Roses, the Crusades, and the Hundred Years War have been my biggest
influences... oh, and some Scottish history as well, such as the
infamous Black Dinner that inspired my own Red Wedding. This isn't a
matter of choice so much as it is one of necessity. I don't have any
other language besides English, and there's a paucity of good popular
English language histories about medieval Spain, medieval Germany, and
the like. I was in Germany last fall, and looked everywhere for good
reference books about the medieval Holy Roman Empire, which would be
treasure trove, I suspect. There are a ton of them that looked
likely... but all in German.
He has however also noted, in the same post, that he doesn't do straight one-for-one transposition of fact into fiction so one can't establish that Starks are inspred from House of York etc.
Q: [Edited for clarity after this point. Ser Loras's (Ser Loras is the nickname of the fan) question concerning whether GRRM borrows from history, particularly Spanish
history, received the reply below.]
George: Well, yes and no. I have drawn on a great many influences for these
books. I do use incidents from history, yes, although I try not to do
a straight one-for-one transposition of fact into fiction. I prefer to
mix and match, and to add in some imaginative elements as well.
He emphasized that point once again in Citadel SSM 950:
The Wars of the Roses have always fascinated me, and certainly did influence A SONG OF ICE AND FIRE, but there's really no one-for-one
character-for-character correspondence. I like to use history to
flavor my fantasy, to add texture and versimillitude, but simply
rewriting history with the names changed has no appeal for me. I
prefer to reimagine it all, and take it in new and unexpected
So in conclusion:
- Yes War of the Roses is an inspiration for ASOIAF.
- There is no history-to-fiction transposition.
- There is no one-for-one character-for-character correspondence.
- The books don't have to follow a historical pattern at all.
While there are several posts including the answers here which are based on observed similarities between Real people and ASOIAF characters however, as Author says, that's not something he tends to do so that makes it guesswork.
For further details, see Historical Influences on GRRM.