Heidi Klum has been passing down her impeccable fashion sense to her kids since they were little.

"We have a rule in the house," the supermodel and Project Runway host once said. "Rule No. 1 is always to look cool, and rule No. 2 is don't forget about rule No. 1. We have other rules … but the No. 1 rule is to always look cool."

Her four kids are all teenagers and tweens now and they are just as stylish as their mom. Klum shares Leni, 18, Henry, 16, Johan, 15, and Lou, 12, with her ex-husband Seal. The children also spend time with Klum's current husband, musician Tom Kaulitz, who considers himself an "extra dad" to the four kids. They even helped Kaulitz plan his surprise proposal in 2019.

"They were so excited and happy for their mom," a friend of Klum told PEOPLE at the time.

While her youngest children stay out of the spotlight — aside from Klum occasionally posting about them on social media — her older daughter, Leni, is following in her mother's footsteps and pursuing a career in modeling.

Here's everything to know about Heidi Klum's four children.

Klum welcomed her first child, Leni Olum Klum, on May 4, 2004, in New York City. Leni's biological father is Italian businessman Flavio Briatore — although his and Klum's relationship ended while she was still pregnant. Klum began dating Seal not long after and the couple married in 2005. Seal officially adopted Leni in 2009 when she was 5 years old.

Before she was even born, Leni had a moment in the spotlight. In an Instagram post for Leni's 17th birthday, Klum revealed that she was four months pregnant with her daughter when she walked in the 2003 Victoria's Secret runway show.

"I am not alone walking down that catwalk here," Klum captioned a video from the show. "If I look close enough then I can see you bumping right along at 4 months @LeniKlum. I loved you before you were born, and I will love you long after I close my eyes forever."

These days, 18-year-old Leni is a model herself, which is something Klum made her wait until she was 16 to pursue. She has participated in many shoots and graced the covers of Rollacoaster magazine, Harper's Bazaar Germany and Glamour Germany. She and Klum also shared the cover of Vogue Germany for the January/February 2021 issue.

The fashion world can certainly be difficult to navigate as a young adult, but luckily Leni has her mom right by her side to advise and guide her.

"I said to her, at the end of the day you have to be happy with yourself," Klum told PEOPLE of the advice she gave her daughter. "And don't do anything you don't want to do. It's okay to say no. You don't always have to please people. But I'm always with Leni. And she has a very good head on her shoulders."

Leni has also made some red carpet appearances with her famous parents. In October 2021, she and Seal attended the premiere of Netflix's The Harder They Fall together, and in June 2022, Leni and Klum were photographed at the premiere of Jurassic World: Dominion.

In another sweet moment, Leni wore one of Klum's dresses from the '90s to her high school prom in May 2022. She captioned an Instagram post of herself, "Prom night in mamas dress 🖤."

After Leni graduated from high school, Klum revealed that her firstborn will be moving to N.Y.C to continue to pursue her modeling dreams and attend college.

The supermodel announced the news on the Today show and couldn't be more proud of her daughter. "She's moving to the Big Apple. It's kind of my first stomping grounds, so I feel like she's doing it all over again. I'm so proud of her!" she said.

Klum's second child, Henry Günther Ademola Dashtu Samuel, was born on Sep. 12, 2005, in Los Angeles. Not long after she gave birth, Klum spoke to PEOPLE about the newest addition to her family.

"Everyone who sees him says, 'Oh my god, he looks just like Seal.' And I'm like, 'He has nothing of me? C'mon, there must be something of me in there somewhere.' And they're like, 'No, sorry, he looks just like his father,' " she said of baby Henry at the time.

A few years later, in 2008, Klum revealed that her kids had a giant costume closet and loved to play dress-up. She also shared that then-3-year-old Henry was comfortable experimenting with all the costumes, including his sister's princess dresses. "There's nothing wrong with that," Klum said at the time, admitting that she also thinks the elegant dresses are "more fun than Buzz Lightyear."

The proud mom spoke about Henry's unique fashion sense again in 2011 in an interview with Good Housekeeping. "He lives in his own world," she said. "We went to dinner all dressed properly [and Henry wore dinosaur slippers]. You can barely walk in those things, but for him, it's not weird at all."

Henry is now 16 years old and like the rest of her younger children, Klum tries to keep him out of the spotlight as much as possible while he is still a kid. However, the supermodel occasionally posts throwback photos of her younger kids or shots that don't show their entire faces.

In 2020, when Henry turned 15, she posted a photo of herself pregnant with him as well as a shot of Henry as a baby. She captioned it, "15 years ago today you came into the world. I feel so proud you are a part of me. You are the twinkle in my eye and the love of my life 🤗❤️ Happy Birthday Henry ... may your birthday be as special today as you are."

Klum and Seal's second son, Johan Riley Fyodor Taiwo Samuel, was born in L.A. on Nov. 22, 2006. The couple announced the news in a post written by Seal on Klum's website. "He is healthy, beautiful and looks just like his mother," the "Kiss from a Rose" singer wrote of his son. The proud father continued, "To our children, a brother/ To our parents, a grandson/ To my wife and I, a son/ To our family, a blessing."

When he was little, Johan was very artistic and loved to draw and paint. In 2013, his drawings and creativity served as the inspiration behind Klum's children's clothing line. "While the other kids are watching a movie, he'll sit down at his desk for 45 minutes and paint monsters one after another," she told Parents magazine of the then-6-year-old. "So he inspired me to create a line around monsters. Johan's very proud he was a part of it. Sometimes he wears his shirt and tells everyone, 'I painted this shirt!' "

Now, Johan is 15 years old. For his birthday in November 2021, Klum posted a video of them together when he was little. She wrote in the caption, "A Heart of Gold and a Mind so Bright. Happy 15th Birthday JOHAN ❤️☀️🎂🥳I am proud of YOU and the young Man you have become."

In June 2021, Klum posted a photo of herself standing between Henry and Johan, both of whom are much taller than her. She captioned it simply, "How did i get so short?"

Lou Sulola Samuel, Klum and Seal's youngest child, was born on Oct. 9, 2009, in L.A. At the time of her birth, Seal wrote in a statement, "It's difficult to imagine loving another child as much as you love your existing children. Anyone who has a family will tell you this. Where will one find that extra love? If you love your existing children with all of your heart, how then can one possibly find more heart with which to love another?"

He continued, "On Friday, Oct. 9, 2009, at 7:46 p.m., the answer to this question came in the form of our fourth child and second daughter. Lou Sulola Samuel was born, and from the moment she looked into both of our eyes, it was endless love at first sight."

In a 2021 interview with PEOPLE, Klum shared that her younger daughter is the only one of her kids who seems to have inherited her love of Halloween. The America's Got Talent judge is known for her huge Halloween parties and epic costumes, and she was hoping to pass the tradition on to her kids. However, most of her kids "couldn't care less" about the holiday.

"I was hoping that I would pass this on even to my kids, but out of four, there's only one that really is going for it and that's Lou," Klum said, noting that Lou dressed up as an Anime character that year with "full on makeup, the hair, all the accessories."

Lou also loves to dance and in August 2021, Klum posted a video of her doing a hip hop routine alongside famous choreographer Miguel Zárate on Instagram.

As with all of her kids, Klum made sure to share a birthday post for Lou. "HAPPY 12 th BIRTHDAY LOU ❤️🥳🎂⭐️💝🌺🥰💎☮️🚀🙏🏻," she wrote alongside some throwback photos of baby Lou. "I LOVE YOU WITH ALL MY HEART."