Rachel added the hashtag, "F*** cancer", appearing to confirm her mother's health problems.
In the photo, Rachel appears to be enjoying spending time with her family over the festive season.
She smiles widely in the photo while wearing a loose-fitting sleeveless black dress.
Jacqui also looked casual chic, wearing a grey shirt, leggings and Nike trainers.
Janine also appeared delighted to be reunited with her daughters, smiling happily.
It is not the first time Rachel's family have personally affected by cancer, as Jacqui has previously battled melanoma.
The cosy living room in Auckland is a world away from the glamorous jet-set lifestyle Rachel usually leads.
It seemed the model, who recently starred in a safety video for Air New Zealand, came without her two children, Renée, 24, and Liam, 22.
Rachel shares the children with her ex-husband, Rod Stewart.
Renée is a graduate of London Contemporary Dance School and appears to be following in her mother's footsteps by signing to a modelling agency.