So, for those who don’t know Star Wars, they had this war that started in Attack of the Clones and ended in Revenge of the Sith. They called it the Clone Wars, because the Republic used an army of clones (slaves, but we’re not gonna get into that) to fight, led by Jedi “Generals” (if they’re Knights or Masters) and “Commanders” (if they’re Padawans – you know, children. ‘Cause child soldiers are always a good idea). The war is covered in The Clone Wars movie and tv series, which are… a thing, but they’re also not what we’re here to discuss.
Some mild genetic deviation is to be expected when creating 3 million+ clones of the same man, especially when said man is of mixed heritage – Mandalorians as a culture tend to accept those from all backgrounds (barring a certain culturally genocidal subset), and as a result tend to be more genetically diverse than most races, and Temuera Morrison, the man who portrays Jango Fett in AoC, is a beautiful Maori man of mixed descent.
Additionally, Clone Force 99 consists of clones who have been genetically enhanced beyond the norm, even for clones. For those not familiar, Clone Force 99, also known as the Bad Batch, consists of:
Hunter, aka Rambo Dad Jango
Crosshair – Uncle Skeleton Jango

The cyborg ghost of Echo
Wrecker looking like Extra Large Jango
and:
Tech resembling a middle-aged, blonde, balding Jango who needs more sun.

As enhanced clones, it makes sense why they’d deviate more from the standard template, but they still manage to look as much like brothers as their ‘regular’ clone counterparts (I’d even go so far as to say they look more like brothers, since the regs actually look more like the same person with slight variations, which, you know, clones.)
And then there’s Omega.
Omega, it is revealed at the end of the first episode, is also an enhanced clone of Jango Fett. Allegedly. You might be forgiven for thinking otherwise, of course, since Omega looks almost nothing like her brothers. She (yes, she) is blonde, fair skinned, and has far more delicate features than any of the other clones. The only similarities I can see are her eye color, and possibly her cheekbones and chin.
Don’t get me wrong. I like Omega. She’s a good kid.
She also looks so different from her brothers that I’m inclined to suspect that, at the very least, Fett’s DNA was not the only DNA involved in her creation.
Time and developing plot may tell what nonsense the producers are up to, if they explain the difference at all, but I’m inclined to keep watching for now.