You and I probably know them simply as ‘Dr Xand’ and ‘Dr Chris’ – the van Tulleken brothers who are both doctors and both TV presenters, and who have done much to bring an understanding of the world of medicine to the public, children and adults alike. But in fact their full names sound rather grander: Jonkheer Alexander Gerald van Hoogenhouck-Tulleken and Jonkheer Christoffer Rodolphe van Hoogenhouck Tulleken. Enough of a mouthful that at the start of their joint episode of Who Do You Think You Are? even they can’t agree on how to pronounce it correctly! ‘Jonkheer’ is in fact a title, indicating minor nobility. We’ll come back to that…

Despite their very Dutch names, the twins, along with younger brother Jonathan, a film director, grew up and were educated in London. And indeed they were born here in the UK, as TheGenealogist’s birth index records attest:

They both went on to study at Oxford – Xand (the one with the beard) at Somerville College and Chris at St Peter’s. But their roots are not here in the UK. Their parents, Anthony and Kit (née Catherine Margaret Hart) met and married in Canada – he is an industrial designer whose roots are unsurprisingly in the Netherlands, and she is a publishing consultant whose father, Gerald F. Hart, was based in Pointe-Claire, Quebec.

Given that Chris and Xand’s male line is so definitively Dutch, I wasn’t expecting to be able to glean any details of their forebears from UK-focused website TheGenealogist (although the site does have a diverse range of records in its International collection)… but I was wrong. Using the site’s powerful MasterSearch tool, simply typing in the surname ‘Tulleken’ actually brought up some really useful finds.

For example, here’s their paternal grandfather, Rodolphe John, listed in the site’s Canadian education records, specifically listed as being a student at Upper Canada College between 1922 and 1926 – and we learn from this that he was based York Mills, Ontario. That means of course that any search for when the family went from the Netherlands to Canada would pre-date 1922.

Interestingly, there’s also an outgoing passenger record at the site, relating to the ship Corsican sailing from Liverpool to St John, New Brunswick, Canada in 1921. The person in question is ‘Jonkheer Hoogenhouck Tulleken’, which of course gives their title and not their name. But we can see that they were 47, born in Holland, and had previously arrived in London from Batavia. Perhaps this was Rodolphe’s father or an uncle, who we might expect to be about that age…? It was definitely a close relative, at least.

The brothers’ WDYTYA journey begins with a visit to their parents’ home, which is filled with family artefacts – significant documents such as a coat of arms, oil painting portraits and so on – although they are unclear about the stories these relate to. One document is in English, and discusses the role of a Jan Tulleken assisting the British navy. So off to the historic Chatham Dockyard in Kent they go, and there’s much to discover.

It transpires that their 4x-great-grandfather Jan Tulleken (1762–1851) was a staunch Dutch royalist who joined his nation’s navy aged only 13, and by 1787 was a captain. The context at the time was a battle for supremacy in the Netherlands between the ‘Orangists’ under William V, Prince of Orange, and the ‘Patriots’ who challenged his authority. Invasion by France in 1795 sent William into exile in Britain… accompanied by Jan Tulleken. To make life simpler, Jan became a naturalised British citizen, and in fact we can turn to TheGenealogist for confirmation of this thanks to its Naturalisation Records collection. This was recorded on 28 July 1800:

Not only do we have confirmation that he chose to be called John here in Britain, but we gain details of his parents: Ambrosius Pieter Tulleken and Susanna Margaretta van Hoogenhouck; and this of course tells us how the two names came together. WDYTYA explores more of Jan’s adventures, from taking a commission in 1802 to his later career back in the Netherlands, and how he came to be elevated to the status of jonkheer, a title passed down the family ever since.

The TV show next goes back in time to the life of Ambrosius, who we learn had worked in the Dutch West Indies, specifically in Demarara, in an area that is now encompassed by Guyana and Suriname. Following this lead reveals a troubling story which is hard for the medical twins to absorb… but you’ll have to watch the show to learn more. Before their adventures are done, there’s another interesting discovery to be made, too, this time in the roots of their 2x-great-grandmother Louise de Bruijn and on the opposite side of the world – this time the Dutch East Indies. It’s quite a journey!