Quote Originally Posted by Archangel View Post
Black hair is a characteristic of the Uchihas, maybe half the village is secretly one of them as well?
Don't be a troll... <__<

Kishimoto himself said it

Madara: "Look at you, you overexerted your powers so much that the Uzumaki Clan's trademark red hair turned snow white"

http://mangastream.com/read/naruto/81065970/17

Kushina, Tayuya, Karin and Nagato are the only red heads on the whole manga (did Nagato's parents had red hair? I think the anime may have messed this up...)