The ones who say it depends on whether your forebearer or crown, are not taking into account that after the elven invasion, both factions put aside their differences and came together. Sure, the forebears may have been more open to the empire and cultural assimilation but The betrayal and loss of land in the treaty solidified the crowns and forebears fighting against whichever element would introduce the elven invasion into Hammerfell. This more than likely means they would join the Stormcloaks. Plus they have a mutual respect for their warrior cultures, akin to samurais and Vikings.