Board Thread:Naruto Discussions/@comment-5054236-20150729184811/@comment-2140588-20150729185545

Gaiden012 wrote: It's more than obvious given their appearances, info on their pages and the official character sheets by the animation studio. Obvious not necessarily means the case. For example, it would be pretty obvious that B is A's brother, given that their appearance is undoubtedly similar. However, they are adoptive brothers, so they aren't even genetically related.

Same case with Might Guy and Rock Lee, who aren't in any way related.