Mark and Scott Kelly are identical twin brothers who have both been into space. Born in 1964 in Orange New Jersey, the brothers were very competitive as children and their parents kept their birth order a secret until they were 16. Mark is older by 6 minutes.

They both graduated from Mountain High School in West Orange New Jersey in 1982. The brothers then took different paths; Mark headed to the US Merchant Marine Academy to study marine engineering and nautical science. Meanwhile Scott went to the State University to New York Maritime College and gained a qualification in electrical engineering.

The brothers then followed different paths to become naval aviators and they both ended up in the same class at the US Naval Test Pilot School in 1993. The school didn't realise they were twins until they both showed up. School officials made the suggestion that one of them lose his moustache so their instructors could tell them apart and it was Scott who sacrificed his mo.

After graduating they both worked as test pilots and were kept on different assignments, often on different sides of the world. Both of the brothers applied to become astronauts in 1996 at NASA, and Scott was the first one to be accepted. Mark also made it into NASA but only on his second application for an interview.

Scott was the first of the brothers to make in into space on 20 December 1999 (Flight: STS-103. Flight Time: 7.97 days).

Mark has been on 2 missions, the first on 5 December 2001 (Flight: STS-108. Flight Time: 11.82 days) and the second on 4 July 2006 (Flight: STS-121. Flight Time: 12.78 days).

On a personal level, Mark was married to Amelia Babis who herself is a fraternal twin, and they had 2 children. The marriage ended, and he now engaged to Gabrielle Giffords a politician in Arizona.

Scott is married to Leslie Yandell and they also have 2 children.