Father Christmas reading with three young children. (Photo by Spencer Arnold/Getty Images). Circa 1915

Young man making the O.K. sign. (Photo by George Marks/Retrofile/Getty Images). Circa 1950s

Attendees at Wizard World Comic Con walk through hallways in Chicago, Illinois, United States, August 22, 2015. (Photo by Jim Young/Reuters)

Young gymnasts practice pull-up on a bar at a gymnasium of a sports school in Jiaxing, Zhejiang province April 11, 2015. (Photo by William Hong/Reuters)

A young Free Syrian Army fighter holds a rifle in Haresta neighbourhood of Damascus January 16, 2013. (Photo by Goran Tomasevic/Reuters)

A young boy lifts heavy bricks as he works at brick factory around Kathmandu valley. (Photo by Narendra Shrestha/EPA)

Two young women embrace in bed together, both wearing white lace underwear. (Photo by Popperfoto/Getty Images)

A young Shiite Muslim child participates in a Muharram procession in Ahmadabad, India, Sunday, October 9, 2016. (Photo by Ajit Solanki/AP Photo)