Sienna Miller celebrated her daughter Marlowe’s 14th birthday on Tuesday. The actress, 44, who announced she had welcomed her third child in May, shared a sweet post on Instagram to mark the occasion – and fans can’t get over their likeness. In the post, Marlowe held up her birthday candles from her cake as the family gathered around the table, while in another snap the teen showed off her best model pose in shorts and cowboy boots. The teenager looked the spitting image of her mother but instead of having Sienna’s signature blonde locks, she had brown hair. Fans wrote: ‘She looks exactly like you!!!! So beautiful’ and ‘Bet that’s your vintage Chloe bag! She looks lovely like mummy’.’She’s your brunette twin!! Beautiful just like her mum’. Sienna Miller celebrated her daughter Marlowe’s 14th birthday on Tuesday. The teen looked just like her mum as she rocked cowboy boots (Sienna pictured right in 2004) Sienna, who shares Marlowe with her ex-partner Tom Sturridge , also uploaded a throwback snap of when she was a baby Sienna, who shares Marlowe with her ex-partner Tom Sturridge, also uploaded a throwback snap of when she was a baby. The exes, who split in 2015, have maintained a close friendship and are often seen co-parenting Marlowe together. As well as Marlowe, Sienna has two children with her fiancé Oli Green, 29. She announced she had welcomed her third child in May, simply saying: ‘It’s happened. I have a tiny baby next door.’ The couple are yet to reveal her third baby’s sex or name.They also have a two-year-old daughter. Sienna announced her third pregnancy by revealing her blossoming bump at the star-studded Fashion Awards in December. In May, she said that she’s surviving on ‘very little sleep’ as she opened up on returning to work just three weeks after giving birth while appearing on The Tonight Show With Jimmy Fallon.During her appearance on the show she opened up about the transition of having another child and spoke about her nightmare flight over to the US to promote new action movie Jack Ryan: Ghost War. The teen looked just like her mum as she rocked cowboy boots. Sienna was the ultimate pioneer of the 2000s Boho-Chic aesthetic, pictured right in 2004) The actress, 44, shared a sweet post on Instagram to mark the occasion – and fans said ‘she is your twin’ Fans wrote: ‘She looks exactly like you!!!! So beautiful’ and #Bet that’s your vintage Chloe bag! She looks lovely like mummy’ As well as Marlowe, Sienna has two children with her fiancé Oli Green, 29. She announced she had welcomed her third child in May She also shares her first photo of the two-year-old daughter she shares with Oli, posting a sweet snap of her toddler’s curly hairSienna said: ‘It feels like stringing sentences together is a bit challenging. I’m on very little sleep but I’m madly in love with my baby.’It’s crazy to be talking words and wearing a dress. What has happened from pajama gate.’ Asked by the host which of her children are tougher to look after, she said: ‘I would have said the teenage girl would be harder to juggle until the transatlantic flight I took yesterday with the toddler and the newborn. ‘The toddler now wins hands down. It was an absolute disaster. There’s no negotiating. I got to the immigration line and just broke down.’Last month Sienna’s sister Savannah confirmed the actress is engaged to Oli. In an interview with Hello!, fashion designer Savannah praised 29-year-old Oli’s beautiful proposal. Savannah said: ‘We are all so over the moon. It’s the happiest news, and it was beautiful, the whole thing. I can’t express how happy I am for her.’Rumours of Sienna’s engagement began the week before when she stepped out with a new diamond ring on her wedding finger.