No friendship is perfect. Katy Perry and Taylor Swift “fight like cousins,” even after they ended their years-long feud. The “Teenage Dream” singer was asked about her friendship with the Grammy winner on the Friday, July 10, episode Capital Breakfast With Roman Kemp, where cohost Sian Welby asked Perry about a theory that she and Swift are ninth cousins.

“Well, we fight like cousins,” Perry responded with a laugh.

The “I Kissed a Girl” singer went on to call the theory “fan fic” before host Roman Kemp told her that “someone has literally written a full thing” about the Perry and Swift’ supposed shared family tree on MyHeritage.com. “Wow, I’m going to have to ask her if this is true or if we should, like, get blood tests together or something,” the American Idol judge said.

Though Perry and Swift started as friends (the “Waking Up in Vegas” singer even performed as a guest on Swift’s Fearless Tour in 2010), the two had a fallout in 2013 after three of Perry’s former dancers left Swift’s tour for the “California Gurls” singer’s Prism Tour, according to Cosmopolitan U.K. In a past interview with The Examiner, dancer Lockhart Brownlie claimed during Swift’s Red Tour, Perry’s management reached out to him and two other dancers—Scott Myrick and Leah Adler—to see if they would perform on the world tour for Perry’s 2013 album Prism. All three agreed to leave Swift’s tour early for Perry’s.

“Obviously we were with Katy for two and a half years, she’s like family to us. So we were, like, ‘Absolutely’. We weren’t really dancing in Taylor’s tour anyway, so I had got a little bored and I really wanted to do a promo tour,” Brownlie told The Examiner.

He continued, “Taylor is very untouchable. When we did see her, we had so much fun with her, but she’s a lot more protected than Katy. Katy’s 28 now and can do her own thing. Her team are so lovely, so we have such a good connection. And this time around she is a lot more in control.”

In a 2014 interview with Rolling Stone, Swift hinted that her song “Bad Blood” from her then-upcoming album 1989 was about a friendship with an unnamed famous friend, which fans believed to be Perry.

“For years, I was never sure if we were friends or not. She would come up to me at awards shows and say something and walk away, and I would think, ‘Are we friends, or did she just give me the harshest insult of my life?'” Swift said at the time. ” “She did something so horrible. I was like, ‘Oh, we’re just straight-up enemies’. And it wasn’t even about a guy! It had to do with business.

She continued, “She basically tried to sabotage an entire arena tour. She tried to hire a bunch of people out from under me. And I’m surprisingly non-confrontational—you would not believe how much I hate conflict. So now I have to avoid her. It’s awkward, and I don’t like it.”

After Swift’s interview, Perry tweeted, “Watch out for the Regina George in sheep’s clothing…” which made fans wonder if Swift’s comments were about her. (Perry, for her part, released the song “Swish Swish” in 2017, which fans to believe to be a response to “Bad Blood.”)

Fast forward to May 2018, and Perry and Swift finally made amends. In May 2018, Swift posted a photo on her Instagram Story of an olive branch and a letter that Perry sent her as a gesture to repair their friendship. “Hey old friend, I’ve been doing some reflecting on past miscommunications and the feelings between us. I really want to clear the air…” the letter started.

In July 2019, Swift confirmed that she and Perry are friends agains after the “Daisies” singer starred in the “Lover” songstress’ music video for her song “You Need to Calm Down.” in the video, Swift and Perry dress as a burger and fries and hug.