3 Referred friends must use your personal link when purchasing the service, and must be new customers to 23andMe. An Amazon.co.uk Gift Certificate (the "Reward") is earned when a kit is shipped to the referred customer. Purchases must be completed within 30 days of referral link activation. Only one Reward is earned per customer referred, regardless of the number of kits purchased. Rewards will be sent on a bi-monthly basis. See Terms and Conditions for more details.