Genealogists and family therapists are like two archaeologists excavating the same site, but searching for entirely different things. The one wants to know who was born when and where. The other wants to know why that still keeps someone awake at night.

Genealogy is one of the oldest sciences of humanity – the ancient Egyptians already kept ancestor lists, probably not for sentimental reasons but because lines of inheritance needed clarification. In Europe it became possible from the 16th century onward through systematic parish record keeping, and since then it has produced an impressive infrastructure: archives, databases, DNA tests, and entire television programmes.

But classical genealogy had a blind spot so large that one only noticed it upon ceasing to look only at the facts: it recorded what had happened, but not what it meant. Born, married, died – that was essentially its vocabulary, and it sufficed for family trees, but not for what stood between the lines.

The genogram added precisely this missing dimension. Suddenly one could ask: why did the great-grandmother marry at seventeen a man twenty years her senior? Why did the great-uncle emigrate to America – alone, without the family, and why did he write only three letters before falling silent? And why did nobody ever speak of Aunt Martha, though she lived in the same village for fifty years?

Invisible Loyalties

A key for understanding these connections was provided by Ivan Boszormenyi-Nagy (1920–2007), a Hungarian-American psychiatrist from Budapest, with a concept as elegant as it is unsettling: "invisible loyalties". He described how family members feel bound across generations by obligations that no one ever voiced – the grandson who takes up the profession of his grandfather who died young, without knowing why, or the daughter who unconsciously repeats her mother's failed marriage, as though following an invisible script she has never read and yet faithfully observes.

These invisible threads only become visible when genealogy and genogram work are combined, and the result is remarkable:

• The genealogical level supplies the facts – who, when, where?
• The genogram level supplies the meaning – why, and how does it continue to resonate?

In Germany this connection was recognized with particular clarity, and for historical reasons that were hard to overlook. The working-through of the war and post-war generations showed: traumas noted in family trees as "fallen 1944" or "flight from East Prussia" continue to operate as emotional patterns in grandchildren and great-grandchildren – even those who never heard a shot fired and never packed a suitcase in flight.