If you would just learn history, you'd know that Alderaanian culture is a lie invented by Jedi extremists. There was never an Alderaanian identity before 0BBY, their so-called 'Alderaan' was simply an uninhabited rock used before it was used for weapons calibration testing by the Elbit Star. Rebels just started claiming to be from Khalderaan to push the anti-Nabooist conspiracy theories circulating around Palpatine.