In pre-Supernova versions, you could choose a Cultural Trait within an Ideology without having to have previously chosen all of the lower traits.  For example, within the Opportunity ideology, I could choose the Recruiting trait without having previously chosen the Ambition trait.  However, in Supernova, it appears that you have to choose the traits in the order that they appear within the ideology tree.  The screen snapshot below indicates (in red text) that I have to choose the Ambition trait before I can choose the Recruiting trait.  Is that correct?  Are you now requiring that cultural traits be selected in order as they appear in the ideology tree?