Mum-of-five Katie, who is known for not holding back about her former flames, made a dig at her footballer ex Dwight, after going through old family photos.
Katie pulled out a few treasured photos she has of Harvey, now 13, in his younger years and shared them with fans on the photo-sharing app.
Alongside one of her posts, the 37-year-old commented on how much she thinks Harvey looked like his dad in that particular picture. She said: "Harvey so looks like Dwight Yorke here."
She then added: "Shame he doesn't want to see him."
Katie also shared another photo of the "first and last time" Harvey had gone to see Dwight play football.
Her posts seemed to divide fans. Some disagreed with Katie publicly outing Dwight, with one user commenting: "Katie, some things are FAMILY matters and should be kept PRIVATE!"
Another claimed Katie had "lowered herself" by hitting out at Dwight.
Others, however, showed their support for Katie and praised her parenting efforts. Many commented that it was Dwight's "loss" and one fan told the former Celebrity Big Brother winner she was a "fantastic mum."
They said: "You have done [a] wonderful job with bringing your family up."
Many more of Katie's followers decided to focus purely on Harvey instead. One person gushed: "Such a beautiful boy." While another commented: "He's gorgeous Katie... it's so obvious how happy he is."
Katie gave birth to her eldest child Harvey back in 2002 and has openly spoken about his disabilities (including Prader-Willi Syndrome) and the amount of care he needs.
In an interview on This Morning back in October last year, Katie spoke candidly about having to care for Harvey 24/7.
She said: "Yes, he is challenging and hard work, but you know, that's part and parcel of having Harvey and I would not change anything."
"He's got such a big personality, he makes me laugh, I love him so much and I know that he absolutely dotes on me," she added. "I think out of all of my kids, everyone always says that Harvey's their favourite because he's just so funny and as he's got older, his personality has come out."
Katie is also mum to four other children. She shares son Junior, 10, and daughter Princess, eight, with ex-husband Peter Andre and son Jett, two, and daughter Bunny, one, with husband Kieran Hayler.
Speaking about being a mum, Katie has previously said: "I'm a great mum. I'm not a conventional mum but I'm a good mum. My kids are happy, polite and respectful."
"I'm always there, we talk about anything," she claimed. "I'd like to come down one day and have ten kids sitting around the kitchen table – that, to me, would really be success."
Meanwhile, back in 2009, Dwight said of Harvey: "I would like to play an integral part in his upbringing, of course, I love my kid but wasn't given the opportunity to really bring him up in the manner I would like to bring him up in. I haven't spoken to, I have haven't seen him in a year. I've gone down the legal route before and I was entitled to see him for a certain period of time and a certain time but she calls all the shots."
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