Right, at the end of the game one of the Viera says to Ritz that she shouldn't be ashamed of her white hair as it shows a connection to the spirit world correct? Viera can use classes like summoners which communicate with spirits. The fact that Ritz has white hair can also mean that she would have the same characteristic ability of the Viera but only in the FF world. In the real world theres a high possibility that she is an albino despite the green eyes.

Theres also the theory that each of the children had a wish and by coincidence most of the wishes could coincide with the Final Fantasy World (plus the fact that it was mentioned after the magic words were spoken from the book). Mewt's wish to not get picked on and have his mother still alive (what better place for this to happen where theres leveling up and phoenix down) yadda yadda, Doned wanting to be able to walk and get over his sickness (probably stayed at an inn or a pub overnight), Ritz not wanting white hair and yet finding a race completly made up of white haired people who help her to get over the fact that she has white hair.

Theres also the theory that has been mentioned that each of the children have an affinity to a race, however this is kinda flawed as Marche doesn't have moogle abilities but helps prove the first theory about Ritz's hair.
Ritz- Viera
Mewt- Nu Mon
Doned- Bangaa
Marche - Humans/Moogles?