In the snapshot, the pair were hugging and wearing matching flowing dresses and at first glance, you could be forgiven for thinking the twenty-something was Nicole, 53.
WATCH: Nicole Kidman is interviewed by Jimmy Fallon from her home in Australia
Lucia wore a hat, and the killer Kidman smile, as she posed with her mum for the sweet photo.
Antonia, 50, posted it to celebrate her firstborn and accompanied the photo with a heartfelt message.
"First born [sic]," she wrote. "There's something powerful about the connection with a first child. It's not favoritism or anything of that nature.
Nicole's niece poses with her mum Antonia in gorgeous photo
"Rather, I think it's because there is a period of time where there are no other beings vying for your love and attention and your focus and devotion is entirely to them."
Her followers called the photo "stunning," and wrote: "Beautiful!! Your daughter looks so much like you and Nicole!" and, "I thought she was Nicole".
Nicole is incredibly close to her mum Janelle and sister Antonia
Others marvelled at the similarities between all three of the women.
While Lucia could likely have a little help to kickstart a career in Hollywood, that’s not what she has planned for her future.
In 2019, she was asked about her plans and she said: "It won't be showbusiness, probably journalism. I am thinking about what I want to do. I am loving uni, it is fantastic, like the best years of your life."
Antonia with her second husband and their children
Her mother is also a journalist and avoided the Hollywood scene to live her life with her four children in Australia.
Nicole is incredibly close to her family though, and in the midst of the ongoing COVID-19 pandemic - when she was allowed to travel - she moved back to her home country from Nashville with her husband Keith Urban and their two daughters.
Nicole has two children with her husband Keith Urban
Discussing being closer to her loved ones during an interview with the New York Times last year, Nicole said: "My sister's staying over and my mum's helping; I don't have that help in Nashville so that's been incredible.
"We never leave the kids, one of us is always there. When Keith went to Nashville and I had to work late nights, I rang Ant and asked her to move in with the girls and she did, and brought along her kids."
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