Van Tulleken brothers

Alexander "Xand" van Hoogenhouck-Tulleken and Christoffer "Chris" van Hoogenhouck-Tulleken (born 18 August 1978), known as "Dr. Chris" and "Dr. Xand' are British doctors, television presenters, and identical twin brothers. They are best known for presenting the children's series Operation Ouch!. Chris has become well known for his two-part television special for BBC One entitled The Doctor Who Gave Up Drugs.  Xand has also presented shows without his brother.

Early life and education
Chris and Xand van Tulleken were born to Anthony van Tulleken, an industrial designer, and his wife Kit, a publisher. Their younger brother is the film director Jonathan van Tulleken.

They are descended from Dutch Rear-Admiral Jan van Hoogenhouck Tulleken (1762–1851; originally Jan Tulleken, of a family traced back to the 15th century, who changed his name in 1822 and was raised to the nobility in 1842 with the rank of Jonkheer, the lowest tier of nobility. The family name is officially without a hyphen, and in the Netherlands the usage of the name "Van Tulleke" is considered wrong (the "van" belonging to the name Hoogenhouck).

The Van Tulleken twins were educated at Hill House preparatory school, then King's College School, an independent day school for boys in Wimbledon, southwest London, followed by St Peter's College (Chris) and Somerville College (Xand) at the University of Oxford.

In June 2023 the twins were the subject of the BBC genealogy programme Who Do You Think You Are?, in which they learned that they were descended from a wealthy slave-trader who had a plantation in Demerara in The Guianas.

Life and career
Both Chris and Xand van Tulleken presented Channel 4's Medicine Men Go Wild, and BBC Two's Trust Me, I'm A Doctor alongside Michael Mosley. Chris was the expedition doctor for BBC Two's Operation Iceberg, and has appeared in Top Dogs: Adventures in War, Sea and Ice (BBC 2), Holiday Hit Squad (BBC One), Museum of Life (BBC Two), The Secret Life of Twins (BBC One), as well as Celebrity Mastermind and The Wright Stuff. Chris was also doctor to a team led by Bruce Parry which recreated the 1911 race to the South Pole in the BBC documentary Blizzard: Race to the Pole. The brothers presented ''What's The Right Diet for You? A Horizon Special''.

Chris van Tulleken was named as an emerging British talent in "The Brit List 2013" by ShortList magazine.

In 2015, the pair presented another Horizon episode, titled Is Binge Drinking Really That Bad?, in which Chris and his identical twin brother Xand tested the effects of drinking moderate amounts of alcohol daily (Chris) and bingeing weekly (Xand).

Chris and Xand appeared on Series 5 of Hacker Time.

In 2016, alarmed by the steep rise in prescription medicine in Britain and dubious as to its efficacy, Chris was featured in the BBC One television show The Doctor Who Gave Up Drugs. It was a two-part social experiment in which he aimed to take over part of a GP surgery and attempt to find practical ways to treat patients and stop patients' prescription pills.

In January and February 2019, they presented a documentary series called The Twinstitute, repeated in 2020.

In Surviving the Virus: My Brother & Me, after contracting COVID-19, Xand was left with an irregular heartbeat.

Personal life
Chris's wife Dinah gave birth to a second daughter in June 2020. Xand has a son from a previous relationship. On 18 May 2023, Xand married Dolly Theis — the former Conservative Party candidate for Vauxhall in the 2017 general election — in London.

Humanitarian aid
Until February 2018, Alexander and Christoffer were patrons and board members of the medical aid and healthcare charity Doctors of the World UK, which is a member of the international Médecins du Monde network. In 2015, Alexander and Christoffer ran the London Marathon for Doctors of the World, raising over £3,400.

Xand van Tulleken was a patron of the medical aid organisation Medical Emergency Relief International (Merlin), which merged with Save the Children in 2013, and reported for BBC Two in the aftermath of Cyclone Nargis, Burma, in 2008.