This comes just after she welcomed her fourth child, another son: His name is Rocky Thirteen.

While Mason, Penelope and Reign’s father is reality TV star Scott Disick, Rocky’s dad is Blink 182 drummer Travis Barker.

Keeping Up With The Kardashians veteran Mason Disick turned 14-years-old on Thursday and his younger brother Reign Disick hit nine. They were both born on the same day, December 14, but five years apart. Their mother Kourtney Kardashian took to Instagram to wish the boys a happy birthday. In one image, she was seen in a green bikini

Before welcoming son Rocky in November, Kourtney would often pose in her bikini

Kourtney also shared a snap of the two birthday cakes for the boys.

Dad Disick posted a photo of a giant silver Mylar balloon banner.

‘Happy birthday boys! You make my life better every day!’ wrote the former party king who reportedly cheated on Kourtney, ending their longterm romance.

Momager Kris Jenner also took to Instagram to wish Mason and Reign well.

‘Happy birthday to my two amazing grandsons, Mason and Reign!!! What are the chances of having two grandsons with the same exact birthday?!?!?! !! You are two of the loves of my heart and I am so blessed that God chose me to be your grandma!!! We have the most precious memories together and I cherish every single one.

‘Mason you are truly so special, kind, sweet, thoughtful, smart, talented, creative and have the best skills on a dirt bike!! Reign you are inquisitive, creative, loving, funny, talented, smart, sweet, and full of energy… I love you both with all my heart !!!’

Khloe Kardashian shared her love for the Disick dudes on her Instagram Stories. ‘Brothers and best friends born on the very same day, I love you.’

Kim Kardashian also shared old photos saying she loved the guys.

Earlier this week Kim shared a photo with Mason.

There were birthday cakes for both Mason and Reign

Kourtneyalso shared this photo of a young Mason and Reign hugging

The boys are very close, and now have another brother named Rocky to bond with

The Instagram snap, captioned ‘Everything’, showed Kim, 43, posing with her children, nieces, nephews, and Scott Disick, 40.

Kim held her youngest daughter Chicago, five, and wrapped an arm around Saint, eight, while North, 10, and Psalm, four, flashed the peace sign.

Mason, who was recently seen grabbing dinner with his family, stood beside his little sister Penelope, 11, and father Scott, who slung an arm over his shoulders.

Fans rushed to the comments section to express their delight over seeing the rarely-seen Disick on their Instagram feed.

Kim Kardashian shared a rare snap of her nephew Mason Disick as she posted several family photos to her Instagram on Monday

Omg WE HAVENT SEEN MASON IN FOREVERRRRRRRRRRR!!!!! Our little internet nephew GREW UP!!!!!!!!!!!!’ one fan posted.

‘Wow Mason had a whole growth spurt. So handsome!’ remarked one fan.

‘Is It Just Me Or Does Mason Actually Resemble Rob A lot?’ another posted.

‘Mason????? Pardon????????’ one posted.

‘Mason is a looking more and more like a junior Rob!! Rightv#??’ one fan remarked.

‘Mason looks like Rob,’ one chimed in.

‘Mason looks so handsome! He looks like a mix of Scott and Robert Kardashian Sr! Is lovely to see him!’ another posted.

Mason is the most low-key of all the Kardashian-Jenner cousins as he lacks a social media presence and is rarely pictured out.

The post also contained this snap of Kim with her daughters

Many fans said Mason resembled his uncle Rob Kardashian

Kourtney previously revealed her son’s aversion for attention: ‘He does not like it. He doesn’t want any part of it. He’s not on social media,’ she said on Not Skinny But Not Fat podcast.

‘He doesn’t love it, and I want my kids to be kids. I crave normalcy as much as we can have it,’ she said.

Mason was notably absent from his mother’s Hulu wedding special, Til Death Do Us Part Kourtney and Travis, however he did attend the nuptials.

Kourtney shares sons Mason, Reign, and daughter Penelope with her ex Scott Disick. She welcomed a son named Rocky Thirteen Barker with husband Travis Barker last month.