Brambleclaw and Squirrelflight ... (Title edited by admin) *BP SPOILERS*
In Bluestar's Prophecy, Swiftbreeze and Adderfang's first litter is Leopardfoot and Patchpelt, then they have Spottedleaf, Willowpelt, and Redtail. Since Vicky said that Redtail is Sandstorm's father in the sixth author chat, Sandstorm and Tigerstar are cousins. (!) Which means Brambleclaw and Squirrelflight are related. o.O
And apparently, since Frostfur and Brindleface are sisters...
Whitewing and Birchfall are second cousins too! Does that count as incest? I guess in a Clan of feral cats, they're all kind of related to each other. I bet the Erins didn't realize what they did when they made Leopardfoot, Patchpelt, Spottedleaf, Willowpelt, and Redtail all siblings. Oi, this is really weird... some other things are that Sandstorm is Spottedleaf's niece and Tigerstar killed his uncle. And then I realized that since Redtail and Spottedleaf are siblings, they have the same blood and are both descended from Spottedpelt and Cloudstar from Firestar's Quest. Which means that his daughter, Sandstorm, Leafpool, Squirrelflight, Hollyleaf, Jayfeather, and Lionblaze all have SkyClan blood. Just an interesting fact... ;)