The mum-of-two said her dad Oscar, a senior officer in the Royal Navy, took a dash of it in his tea and she has proudly continued the tradition.
The singer and model, 35, who has two daughters, Ava, five, and Hero, two, said: "Come on, it's normal... I made everyone try mine. It tastes just like those probiotic yoghurt drinks.
"Sweet – but not as sweet as condensed milk. I grew up knowing that he did that so it's not weird to me."
She laughed: "I sound like a happy-clappy hippy. Oh well, now you know. We're that kind of family."
She was giving in an interview to the Evening Standard about her role as ambassador for charity The Big If London, calling for G8 leaders to tackle world hunger.
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