Board Thread:Wiki Discussions and Support/@comment-995176-20141123043523/@comment-2140588-20141213194153

Going with the Child -> Parent -> Grandparent cycle, this is why:

Naruto (1/4), Hinata (1/4) Kushina (1/8), Minato (1/8), Hiashi (1/8), Hinata's Mother (1/8)

Naruto + Minato -> 3/8 & Hinata + Hinata's Mother -> 3/8, while Kushina and Hiashi are both 1/8.

If i did the math correctly, there was a higher chance for an offspring to have Naruto or Hinata's hair colour because of their genes. At least this is my opinion on this whole thing..