You could sign up under one set of rules and find yourself bound by significantly different terms — including changes to how your data is used — simply by continuing to log in without reading a notification email.
By agreeing to these Terms, you waive your right to participate in class action lawsuits against 23andMe and must resolve most disputes through individual arbitration, which significantly limits your legal recourse. Your payments are generally non-refundable, and 23andMe may use de-identified versions of your genetic data for research purposes. You can opt out of the arbitration clause by sending written notice to 23andMe within 30 days of first accepting the Terms.