Hinata and Neji are genetically siblings...

[Sonzumaki]

Hinata and Neji's fathers (Hiashi and Hizashi) were twins, so they have the same exact genetic makeup. Making half of Hinata and Neji's genes...the same. Like half-siblings.

Think about it : O

 

[Ryóma]

Makes sense.

 

[Neji Hyūga2]

I thought that was obvious, considering she called him brother (aside from the traditional way of talking about family). Plus a lot of people in Naruto just breed within family.

 

[Defence]

They do look alike

 

[ROBOTICSUPERMAN]

They do both have those funny coloured eyes

 

[LilyRose]

Yes, genetically speaking, they are essentially just born from different mothers. Socially, that's a whole other story.

 

[Zavage10]

Yep half siblings

 

[Kakooli]

That disgusting alien incest clan should have been genocided instead of the Uchihas.