On Sunday's Life of Kylie, Kylie Jenner revealed that her signature plump lips came as the result of a boy assuming she'd be a bad kisser

Despite having a multi-million dollar cosmetics empire, nearly 100 million Instagram followers, and being part of one of America’s most famous families, Kylie Jenner still fell victim to the opinion of a boy she liked as a teenager.

On Sunday’s episode of Life of Kylie, the reality star revealed that her signature plump lips — which she admitted to having injected after spending years overlining her mouth — came as the result of a boy assuming she’d be a bad kisser because of her naturally thin lips. While Jenner now feels comfortable with the size of her lips, the 20-year-old admits she still struggles to earn the approval of mom Kris Jenner.

The two butted heads during a trip to Peru, where the cosmetics mogul went to visit children who benefitted from the donations of her Smile lip kit (100 percent of the proceeds went to nonprofit Smile Train and helped 1,300 children with cleft lip and palate conditions as of her visit). Kris got frustrated when her daughter spent the weekend before their excursion in Miami with an unnamed guy she was dating and made the momager pick her up before going to South America — adding five hours to the trip.

“I’m happy she’s dating,” Kris tells Kylie’s assistant Victoria Villarroel on the jet. “And I want her to enjoy herself and have fun, but she needs to be able to still focus on the details and the important things.”

Once in Peru, the 61-year-old complained that Kylie’s hotel room was too messy and told her to “play ball” at a Michelin starred restaurant where the Smile Train team hosted a dinner for the lip kit maven. Kylie and her best friend Jordyn Woods ultimately dipped out of the dinner early in search of other food. But after visiting 3-month-old Mia in the hospital ahead of her Smile Train-sponsored surgery, Kris and Kylie and got on the same page about how Kylie lives her life and runs her business. Read on for what the E! star said about how meeting Mia affected her outlook, why she’s not scared to make mistakes, and her surprising favorite food.

On how a teenage boy made her want bigger lips…
“I was 15 and I was insecure about my lips. I have really small lips. And it was like one of my first kisses and a guy was like, ‘I didn’t think you would be a good kisser because you have such small lips.’ But I took that really hard. Just when a guy you like says that, I don’t know, it just really affected me. I just didn’t feel desirable or pretty. I really wanted bigger lips. I would overline my lips with lip liner just to create the illusion of bigger lips. And then finally I was like this lip liner isn’t doing it. [I] ended up getting my lips done.”

On her relationship with Kris as a kid
“I was scared of my mom growing up. She was really scary. She still is scary but now we have more of a friendship.”

VIDEO: Kylie Jenner Channels Her Inner Barbie in New ‘Flaunt’ Magazine Photo Shoot

On working with her mother…
“My mom does tend to take over a lot in my life. We do things differently sometimes. It gets frustrating because she doesn’t realize that I got it. I’ve got it under control. I feel like sometimes my mom just doesn’t know who I am.”

On feeling like the odd one out in her family…
“I’m not like either of them. I butt heads with my parents and Kendall, but they’re three Scorpios against one Leo in the house. It’s like we’re the worst signs to be together. We’re like not compatible. We just all have strong personalities so it’ll always be them against me.”

On her thoughts about eating alpaca’s heart, fish scales and ash-covered potatoes at Central Restaurante in Peru…
“That food is just not for me. That’s all I’m going to say.”

On the one food she loves…
“I eat shrimp tacos everyday. I actually learned this recipe from Karrueche Tran. We did it on my app. She taught me and I kind of just fell in love. The tacos, the guac, the onions, the shrimp, the shell. The juiciness drips down your lips. Mmm, shrimp.”

On working with Smile Train
“When I was younger, I definitely didn’t have the best confidence at all. These kids have it on a whole other level. So Smile Train touched me and I felt the urge to get involved. It’s amazing to know that the money I’m donating is actually doing something, changing lives. But it is heartbreaking to know that there are so many people who just don’t have the resources. I couldn’t even imagine what Mia’s mom is feeling right now. I couldn’t fathom having a baby that’s going to go under … do this surgery. It must be such a scary feeling. This experience really made me appreciate my family and our health. And I think my mom is starting to trust me. It might not be the way she does things, but I think she trusts that I’m handling myself and my business on my own.”

On why she doesn’t mind messing up…
“I’m trying to not grow up too fast. I love my age. I love my fans. I love that we’re all young — the new generation. I want to make mistakes. I want to make bad decisions and learn from them. That’s the only way I’m going to grow.”

Life of Kylie airs Sundays at 9 p.m. ET on E!