Early-life: Born John Mark Galecki on April 30, 1975, in Bree, Belgium. His mother was a mortgage consultant and his father was in the US air force, before becoming a rehab teacher for blind war veterans. The family moved back to America when Johnny was three. He got his first acting role in 1987, in the made-for-TV movie Time Out for Dad, which was the first of several bit parts in a variety of TV projects. Johnny debuted on the big screen as River Phoenix's brother in A Night in the Life of Jimmy Reardon in 1988.

Early-life: Born James Joseph Parsons on March 24, 1973 in Houston, Texas. Jim was determined to become an actor from the age of six, after performing as the Kola-Kola bird in a school production of The Elephant's Child. After graduating from high school, he studied for a bachelor's degree at the University of Houston. He was accepted onto a two-year course in classical theatre at the University of San Diego in 1999 and, after graduating in 2001, he moved to New York.

Early-life: Stephen William Hawking was born on January 8, 1942 to Frank Hawking, a research biologist, and Isobel Hawking. He had two younger sisters, Philippa and Mary, and an adopted brother, Edward. In 1950, the family moved from London to St Albans in Hertfordshire, where he attended St Albans High School for Girls between 1950 to 1953 _ at that time boys were educated at the Girls' school until the age of 10. From the age of 11, he attended St Albans School, where he was a good, but not exceptional, student. He enrolled at University College, Oxford, his father's college, with the intention of studying mathematics, although his father preferred he go into medicine. Since mathematics was not offered at the college, Hawking instead chose physics.