Thomas Markle's granddaughter said the child sex allegations he faces are 'not a surprise', adding that she always felt there was 'something off' about him.
Noelle Rasmussen, niece of Meghan Markle, made the astonishing claim just days after police in the Philippines revealed they were investigating the 82-year-old over allegations he had 'hundreds, if not thousands' of child sexual abuse images.
One of the photographs is alleged to show an image of Mr Markle having sex with an underage girl.
The Philippines' interior minister Jonvic Remulla said Mr Markle appeared to be 'a possible sex offender of the grossest kind'.
Mr Markle has denied any wrongdoing, admitting he paid for sex in the Philippines but insisting it was only with adult prostitutes.
His ex-wife Roslyn Loveless - and Ms Rasmussen's grandmother - is also understood to have sent a letter years earlier to the Metropolitan Police alleging he was a paedophile in January 2019, before its contents were passed on to Prince Harry and Meghan.
Ms Rasmussen, who recalled her late grandmother writing the letter, described the failure of Scotland Yard to pass on the allegations as 'embarrassing' and revealed she was not entirely surprised by the claims.
Noelle Rasmussen said the child sex allegations her grandfather Thomas Markle faces are 'not a surprise' and she always felt there was 'something off' about him
Mr Markle denies all of the allegations. Authorities in the Philippines are currently investigating
Speaking to The Telegraph, she said: 'Maybe it was a vibe that I subconsciously got… something's not right about a person, and you don't actively register it.
'But your body tells you when something's off.'
She added: 'The more and more I think about it, it just doesn't… I don't know why it's not a surprise.'
Ms Rasmussen added that she '100 per cent backs' the Duchess' decision to distance herself from her father.
However Ms Rasmussen's mother, Samantha Markle, has dismissed the claims.
Meghan's half-sister said previously that if her mother had sent the letter it was out of 'hatred and bitterness', and accused her of being an alcoholic and 'not credible'.
Mr Markle and Ms Loveless divorced in 1975, four years before he met Meghan's mother Doria Ragland.
It is understood that the Met is assessing whether to refer itself to a police watchdog over its handling of the letter.
Mr Markle's ex-wife Roslyn Loveless is understood to have sent a letter to the Met Police in 2019 accusing him of child sex abuse
In photos obtained exclusively by the Mail on Sunday, Mr Markle is seen in a Florida hospital after having his leg amputated earlier this year
Meghan Markle pictured in 2011 with her father Thomas who faces child sex abuse allegations
Meghan and her father have been estranged since at least 2018 when she married Prince Harry.
Their relationship broke down after he admitted staging paparazzi photos of himself prior to the wedding.
The Duchess wrote to him last December after his leg was amputated in the Philippines, allegedly telling him he posed a risk to children and would never be allowed to meet his grandchildren, Archie and Lilibet.
The Daily Mail has contacted the Metropolitan Police and Meghan Markle's representatives for comment.