King Charles and Princess Kate share a deeply personal battle with cancer. And now, a newly uncovered historical link shows their families were united in that fight long before either was born.

According to research uncovered by Australian historian Michael Reed and reported by The Telegraph, ancestors of the monarch and the Princess of Wales worked together nearly a century ago to advance cancer research. In 1925, King Charles’ great-uncle, the sixth Earl of Harewood, and Princess Kate’s great-great-great uncle, Sir Charles Lupton, helped establish the British Empire Cancer Campaign’s Yorkshire Council.

The discovery comes as both royals have faced cancer treatment in recent years. Kate is now in remission following chemotherapy, while the King is expected to scale back his treatment in the new year.

Reed found that Viscount Henry Lascelles served as the council’s first president, with Sir Charles Lupton acting as its vice-president. Princess Mary, King Charles’ great-aunt, later took on the role of president until her death in 1965. Their work is being marked with a centenary booklet titled “a century of saving lives,” alongside a commemorative ball at Castle Howard.

“I felt it was very poignant that although the Princess and King Charles’s ancestors were both aristocratic men, they chose to get their hands dirty doing really tough campaigning for a disease which, in 1925, perplexed most leading scientists,” Reed said.

He added, “I think this new knowledge of both their families having an historically strong connection to cancer research will add to both the King and Princess’s determination to continue fighting the disease.”

Earlier this month, the King echoed that commitment in a Stand Up to Cancer message, saying, “I know from my own experience that a cancer diagnosis can feel overwhelming,” while urging the public to prioritise early screening.