prince william princess diana
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Prince William celebrated his 36th birthday yesterday, but the occasion was bittersweet, considering its connection to his late mother. Princess Diana was 36 when she died in a car crash in Paris in 1997.

Royal commentator Victoria Arbiter pointed out the connection on Twitter: “I’m sure it’s not lost on William that today he turns the same age his mother was when she died. Many people who’ve lost a parent at a young age have said its a very odd feeling to reach that milestone.”

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The Duke of Cambridge spent part of his birthday yesterday speaking at the handover of the Defense and National Rehabilitation Centre, a rehab facility for recovering Armed Forces personnel, but perhaps his mother was also on his mind.

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Last year marked the 20th anniversary of Princess Diana’s death, and William and his brother Prince Harry honoured her memory by sharing never-before-seen photos from their childhood and giving rare interviews about their memories of her. “Our mother was a total kid through and through,” Harry reminisced.

Now that William is a father to three young children—Prince George, 4, Princess Charlotte, 3, and Prince Louis, 2 months—he ensures his children are also aware of their late grandmother’s legacy. He said that while putting his kids to bed, he talks about Diana “and try to remind them that there are two grandmothers in their lives.”

The night before the 20th anniversary of her death, William, Kate Middleton, and Harry also visited the White Garden at Kensington Palace, which was renovated to honour their mum.

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This article originally appeared on Harper’s BAZAAR US