How would blockchain voting address the ability to give your votes away prior to the election? (Or does it?) For example, if I have one "votecoin" that I vote

How would blockchain voting address the ability to give your votes away prior to the election? (Or does it?) For example, if I have one "votecoin" that I vote with that isn't tied back to me (as per necessity of private voting), how can the system ensure that it's actually me voting, and not just whoever I gave/sold my vote to beforehand?