That's the other thing: this new "revelation" is about something discussed during production of the movie. The Lion King is no different than any other movie in this simple regard: before the final product is actually finished, ideas are created, discussed, modified, and finally, left in or thrown out entirely.
As it was already pointed out, Scar wasn't originally intended to be a member of the pride, but an outside rogue. That idea was quickly thrown out to make the story more personal by having the main villain be within the pride itself, and not outside of it. That being said, it's easy to see how this original idea could have lingered in the production team's minds, thus giving us this "Mufasa and Scar are not brothers" 23 years too late.






They are literal blood brothers as established in the movie. Scar says "my big brother." If they weren't related Scar wouldn't have this exchange with Mufasa. Mufasa also says "Scar, brother help me!"
Biological lions and anthro lions are nothing alike. The whole "Simba and Nala were siblings" thing is so bunk it's not even funny. Disney went to great (to me absurd) lengths in SP to make sure we knew Kiara and Kovu were not related and couldn't be first cousins. Why in the world would anyone think Disney would do incest
This is silly to say just because they don't look alike they can't be brothers. Have you seen how different siblings from the same mom and dad can look? It's even more varied in mammals (different males can father kittens and puppies for instance).


