Not rare. Approximately 80% of people have a brother or sister. On average siblings are less than three years apart, and share 50% of their genes. Children from

Not rare. Approximately 80% of people have a brother or sister. On average siblings are less than three years apart, and share 50% of their genes. Children from the same parents tend to look alike. Apple has researched this: > The probability that a random person in the population could look at your iPhone X and unlock it using Face ID is approximately 1 in 1,000,000 (versus 1 in 50,000 for Touch ID). […] The probability of a false match is different for twins and siblings that look like you as well as among children under the age of 13, because their distinct facial features may not have fully developed. https://9to5mac.com/2017/09/27/face-id-iphone-x-white-paper/ https://9to5mac.com/2017/09/27/face-id-iphone-x-white-paper/ Family members unlocking phones documented previously: https://www.theverge.com/2017/11/14/16650394/10-year-old-unlock-mom-iphone-face-id https://www.theverge.com/2017/11/14/16650394/10-year-old-unl... http://mashable.com/2017/10/31/putting-iphone-x-face-id-to-twin-test/ http://mashable.com/2017/10/31/putting-iphone-x-face-id-to-t...