I don’t know my great aunt’s full name or her date of birth. And so I’ve always feared that the family story about her - that she died in a Bolshevik riot in her native Warsaw -  would remain vague and just out of touch. All I have are a few photographs.

But this week I had the chance to talk to Crista Cowan of Ancestry.com, who knows everything there is to know about family history, and Jewish families in particular. If anyone can give me that ‘Who Do You Think You Are?’  moment it’s Crista. She’s here in London for the annual international Jewish genealogy conference which starts on Monday, and she’ll be sharing her knowledge with 800 people from more than 20 countries who are attending. She’s a superstar in the genealogy world -  “Wow!” said my friend, a keen roots researcher when she heard who I was meeting.

Despite the surname and specialism, she’s not Jewish herself.  But when she was building a career in tracing roots, she advertised at her aunt’s gift shop, which happened to be in a very Jewish neighbourhood in Los Angeles. She quickly built up a detailed knowledge of the specific challenges facing Jewish families who trace their history – historical and psychological. Jews know that very often the stories they uncover will be grim. “History is messy,” says Cowan. But she believes firmly that “bringing it out into the sunlight” can be very healing for families.

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The author's great grandmother and the great aunt believed to have died in a Bolshevik riot (Keren David)

She cites work that Ancestry has done to give DNA tests to thousands of Holocaust survivors, many of whom believing that they are the only members of their families left. In some cases this has led to family reunions after decades apart.

I ask for tips for people starting to build their family trees. First, she says write down everything you know. “Every detail. The way that grandpa said a certain word in Yiddish can be relevant. “

Next, interrogate “everyone”. The older generation, of course, but also cousins who may have had access to memories and people that you didn’t know. Then start doing research using the many records available, including immigration records and censuses. New information becomes available all the time.

Once you find your family in the records, look at the people around them. New immigrants often lived near relatives and people from their hometowns. So the names and birthplaces of neighbours may fill in crucial gaps of information.

Pay special attention to names. Often Jewish families had multiple versions of their names -  say, Lithuanian, Hebrew, anglicised versions. Siblings might have different versions of the same surname. So try and collect all the variations to help you work with the records.

And then there’s geography. Shifting borders mean that a location might have been part of any number of countries -  and therefore the information about your relatives might be in a different archive than the one you expect.

Newspapers -  the Jewish Chronicle being a prime example -  can be an excellent source of information “and one of the most underrated” says Cowan. Thanks to the Jewish Chronicle archive I’ve found the exact addresses where my grandparents were living when they got engaged, and lots of other details.

Hurray for the Social and Personal column, through which you can trace the history of most British Jewish families, and boo to Facebook which has somewhat superseded it in recent years.  But there are also family history details to be found in other papers too -  in one of my great-grandfather’s case, a rather shameful history of extremely petty crime in the days when fare-dodging on the Underground made a small story in the evening paper.

So - can Cowan find my Bolshevik (or not) great aunt? The only Bolshevik riots in Warsaw were in 1920, she tells me, which sounds about right as my grandfather was born in 1890. Through Ancestry.com she accesses the Jewish Records Indexing Poland project, a volunteer-led digitalisation of Poland’s lost Jewish community. She types in my grandfather’s surname -  warning me that perhaps my great aunt had married, and so changed her surname. And lo! A list of people with the right surnames appears, although, in the limited time available, we can’t find the exact match I’d hoped for.

Not to worry -  I’ve got the bug. Hours of research lie ahead…but I’ll track her down, I promise.