The Chicago star, 51, wished them a happy anniversary and posted a throwback picture from their big day.
She captioned it: "54 years ago today, my Mam and Dad tied the knot and began their wonderful journey as Husband and Wife![sic] I love you both."
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Her followers loved the black and white photo and commented on the remarkable resemblance she has to her mum, Patricia.
"You look like your mum in this beautiful picture," wrote one, while another said: "Wow, no wonder you are so stunning. Cheekbones."
Catherine - who was born and raised in Wales - is her mum and Dad, David's, middle child. She has an older brother, David, and a younger brother, Lyndon.
Catherine wished her parents a happy 54th wedding anniversary
Catherine is incredibly proud of the close relationship she maintains with the family she was born into, and also the one she has created with her husband, Michael Douglas, 76.
The pair are proud parents to Carys, 17, and Dylan, 20, and they will celebrate their own marital milestone in November too.
Catherine and Michael will ring in 20 years of marriage and she already has plans for how they will celebrate.
Catherine and Michael will soon celebrate 20 years of marriage
"I will raise my mask and let my husband passionately kiss me, then I will put it firmly back on," she told People magazine before confirming the coronavirus pandemic has put the kibosh on any grand plans.
"We won't be doing any great big party," she added. "Not that I'm a big party fan anyway. It would be nice to get all our friends together in one space, but we're not doing that until we're completely out of the woods."
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