My thoughts and proof on the matter
I know i'm probably going to get in a huge fight for this, but i'm going to take a stab at it anyways. Any official information about the directors words on the matter have been contradicting themselves and by other material or people who claim to have met someone who worked on SP have nothing but their words, words that could've been altered.
Most people immediately assume since Kovu isn't Scar's son, Nuka and Vitani must be his two kids since the information was never decided for them. However, you must realize this information was never confirmed either, leaving it open to some debate.
As I look about the Pro-Scar's children fans they seem to have more proof pointing to Scar as the father.
When I look to the Anti-Scar's children fans, they can really only point out it was never said in the movie.
As a Pro-Scar's children fan, I think this is very weak evidence. Just because the information was left untouched, doesn't mean it's not true. On the flip side, it doesn't mean it IS true.
Nuka is Nunka
During production, there was no Kovu or Vitani, only 'Nunka', the exiled cub of Scar and Zira(then named Bianca). Nuka is not an actual name, it's a word in Swahili and words, just like in any other language, can spelled incorrectly. 'Nunka' was obviously mispelled. As a whole, it doesn't mean anything. The magazine, named Variety had a few mistakes(such as calling Simba and Scar brothers) and spelling Nuka wrong was one of them. I know it's a mistake because look here http://kovu-online.webs.com/imnuka.jpg , the Nuka cub toy(no it's not a completely different character like everyone thinks it is) looks nothing like Nuka, but it's got the name right at least. Like 'Nunka's' role in the story, his design was still being worked on.
Betrothing Nuka to Kiara(then named Aisha) would obviously be incest: the two would be cousins so a new character was to be made.
And that is Kovu
The script has been changed, but not drastically and with many movies, the unknown info can found in the credits of the script. Right off the top of my head: Sarafina's name can be found in the credits, Esperanza, the horse from "Stallion of Cimmiron", name is only mentioned in the script. For a fairly recent film "How to Train You Dragon", Hiccup's full name can be found in the DVD's contents(as well as in the book).
Nunka is Scar's son, Nuka is Nunka, Nuka is Scar's son.
Scar's likeness to Vitani and Nuka:
The most powerful arguement us Pro's have: Vitani and Nuka resemble to Scar, and not just a little bit. ALOT, especially in Nuka's case. Both Vitani and Nuka have dark eyeshades around their eyes like Scar, something that Zira lacks. Both Nuka and Vitani have freckles, something both Zira AND Kovu lack, and that I think Scar had as a cub. It makes sense: These freckles disappear from Nuka when he becomes an adult, and Vitani gains them when she becomes a young adult.
Males and females are opposites in the TLK world:
*Males lose their ear rims as adults(see Simba and Kovu)
*Females gain them(see Vitani and Possibly Kiara if she is "Fluffy")
*Females gain freckles(if they have them) as adults(see Vitan and "digger")
*Males lose them(see Nuka and possinly Scar)
*The tuft of a male gets larger, more prominent and eventually turns into a mane(See all males)
*The tuft of a female cub gets smaller as she ages(see Vitani)
*Females get darker than males as they age(See Nala, Sarabi, and Zira)
*Males generally stay the same color(See Kovu, Nuka, and Simba)
Distinct differences from their brother Kovu
When you watched the movie the first time, you may not have noticed the many pridelander traits in Kovu. He's buffer than the rest of the outlanders, which could've very well been from his 'training'(pfft) but Zira said his training would intensify and she would've pushed him the hardest out of her three children. His claws don't extend and his paws are rounded like Simba's and Kiara's as opposed to the long toes Nuka, Vitani, Scar, and Zira have. Actually all the outlanders seem to have the long toes so they can make hand gestures, something Kovu doesn't do once in the film.
Nuka boasts a black mane no other lion in the TLK universe shares except Ahadi(possibly). Sure, a rouge could've mated Zira, as they have been confirmed to Exist in the TLK universe(King Joe, Ni, Kovu claims himself a rouge) but Nuka was born during Scar's reign. WAY before Vitani and Kovu were concieved(he was at least 2 years of age- A teenager). Had Nuka been the son of a rogue, Scar would've killed him. Not only was he a threat, he was useless anyway.
*Body gaurd? No, he was weak and not to bright.
*King? Of course not. Even ZIRA disagrees with her son being heir('I could be a leader if she'd just give me a chance, 'If Kovu is so special, why does he need us? I never even had a chance!')
*Border gaurd? Again, he was weak, what could he do against a rogue besides flee?
Scar allows Nuka to live because of the simple fact he was his son. He was simply never to be king, which would explain Nuka's distaste for Scar in SP.
So why does he never refer to Scar as his father?
For a variety of possible reasons:
*They didn't tell him
Nuka says ZIRA is the one who never gave him a chance. While one could say Scar also never gave him a chance and since he's dead the choice was left up to Zira and she denied him the throne since she would never go against Scar's order, I would like to point out he doesn't say 'they' only 'she'.
If he never knew he was Scar's son, he couldn't have used it as an argument to justify he was the real chosen one. Which is why he says what he does in the film.
He's the oldest.<-- his first and most compelling argument. He's basically saying: "Well none of us are Scar's children, how come Kovu got chosen over me?"
*Why wouldn't he tell?
Well, Scar's whole aim was to become king. And his goals after that were to prove he was better than Mufasa. He wanted to be loved and adored, he wanted to be better than Mufasa, and he wanted to continue on his name...
Well clearly he wasn't loved, so he moved onto the next two things.
Simba was a normal, healthy cub. He was lively, strong and grew to be athletic and strong. But Nuka...?
Judging by his condition and how he doesn't seem to get much bigger than his young adult sister as a full adult himself, one can safetly say he was born a runt. The termites plaguing him aren't really an argument, no trace of them are seen once he's a full adult.
Him and Teen Simba(the one seen briefly in TLK not 1 1/2. There Simba was an adoloscent) are the same age but he lacks the mane fur on his chest so he's underdeveloped. When they're the same age, Nuka's mane hasn't puffed out or thickened or anything. It just filled in.
He wouldn't have been acceptable to Scar and if Scar doesn't like him then Zira really wouldn't have liked him either. Scar disowned Nuka, a weak cub that was his own, in favor of Kovu, a strong cub that wasn't his. He took the better of the two, Kovu.
Wouldn't Nuka had figured it out?
Despite the fact he's my favorite character, I will admit he's not too bright. Like an idiot, he leaps up the unstable dam while no else does(and Zira even gives a look for it like 'ugh').
Then of course when he surrounds himself in fire.
Oh and when Kovu doesn't attack Kiara he angrily yells 'HE LET HER GO!' when the whole plan was to get Simba through Kiara, so she had to be alive, and killing Kiara would screw everything up. He's not at all quiet about this either.
So no, Nuka never would've caught on unless it was bleeding obvious.
However Nuka's comment of "Kovu, Kovu, Kovu, Scar wasn't even his father" seems to lean away from this argument. Why would Nuka be angry Kovu was chosen over him if he wasn't Scar's son himself?
Nuka didn't accept Scar as a father
Out of all of them, Nuka is the most like Scar. He doesn't seem to be loyal to the lion, openly displaying his disgust for Scar when Zira mentions him. Evryone else however IS loyal to Scar. Nuka isn't, he's in this game for himself.
If Nuka wasn't Scar's son, Zira would've killed him. After all she threatens to kill Vitani, her own useless daughter(Quote from SP book: "Girls will be girls...but sons will be Kings!") why would she need a useless son that obviously threatened Kovu's position?
Scar denied Nuka the throne with no chance on getting it back, he denied Scar as a father and thus never referred to him directly as such. Simple.
Vitani's likeness to Scar
I can understand everyone's reluctance to believe Vitani is Scar's daughter. But I met you all would believe she was the daughter of Scar if it weren't for those blue eyes of hers. Go on. Just imagine her with green or red eyes for a second.
I bet she looks alot more like Scar's kid now: http://s1123.photobucket.com/albums/l554/Werebereus/?action=view¤t=Cheifhog.png
But nevermind that. When debating who vitani's father is, the question of where he eyes come from is usually brought up. You all seem to ignore the fact eye color CAN be inherited from grandparents in the lion king.
Simba's eyes are Orange like his mother's. http://www.animationsource.org/sites_content/lion_king/img_screenshot/17276.jpg
Nala's eyes are blue like her father's(presumably. And yes, blue. People can seem to get that through their thick skulls!).
http://www.animationsource.org/sites_content/lion_king/img_screenshot/19016.png (yes even in 1 1/2 her eyes are blue)
Yet Kiara's are red like Mufasa's.
Obviously she inherited them from him, so why can't Vitani get hers from a grandparent? I think she got them from Uru, who I believe has blue eyes just like her(and Mufasa's red eyes were inherited from Mohatu).
Ignore her eyes and look at her shape. Like Scar, Nuka, and Zira she has a long muzzle with a warped demented smile and sharp triangular teeth. Her eyeshades are not only dark like Scar's but they have the same shape. Her ears are and drooping like Nuka's and Scar's and she has earstripes that no one else has. This could also be a trait from Scar taking into account the males/females thing.
Unlike Kovu, her claws stay extended for the entirety of the movie(except when she's a cub. Claws only come in when the lion/lioness is an adult).
Her coloring and head tuft could've came from Zira. As she ages, it becomes less and less prominent so, assuming Zira is an older lioness, she could've had one as a teen(that's actually a nice mental image/idea...) that eventually receeded away.
Vitani's attitude towards Kovu
Vitani doesn't seem all that displeased with the idea her brother/half-brother will be king. She seems excited actually, as shown in the song 'My lullaby' and when she watches Kovu follow Simba into the den(which was creepy btw) Like Zira and Probably Scar, she blantantly tells Nuka to his face he can't be a leader by saying 'Yeah right' when he says he can and ignoring him when he rants about it again in the graveyard.
So if she's Scar's daughter and the firstborn of the two why isn't she fuming like Nuka?
Well...I honestly doubt Zira would listen to her daughter's complaint. That and the two don't have much of a relationship anyway. That and she seemed to just want to watch Simba die.
And if she WASN'T Scar's daughter?
Well...judging from Nala, he'd probably kill Kovu, wait for her to mature and put the moves on her. It makes sense. For a lioness to become receptive her cubs must be killed.
Scar wasn't going to kill his own cub just to get rid of another as he doesn't hurt the useless Nuka. But Vitani was a girl...so Kovu would have to do. It's never said if Scar was overjoyed at the site of some cub who looked like him. They just said he was picked. Disdainfully? Reluctantly? Who knows?
Conclusion: Nuka and Vitani are the kids of Zira and Scar. Nuka was unacceptable due to the fact he was weak and Vitani was unacceptable due to the fact she was a girl, but Scar, unwilling to murder his daughter or have someone else do it, disdainfully chose Kovu as his heir, coming to the conclusion no one else would want him as a mate and he and Zira couldn't produce any worthy heirs due to his bad genes and the drought.