The f(x) girls were recent guests on the June 16th episode of MBC's Radio Star variety program where Krystal revealed her troubled past with her elder sister, Jessica from SNSD. Shin Jung Hwan had asked Krystal as to what Jessica was sorry to her about, having apologised and cried once on broadcast about her. Krystal explained, "Even though we were sisters, we had a lot of quarrels back then. Like clothes� or .. she took my money." Shin Jung Hwan then asked if they shared the same style of clothing, to which Krystal replied, "We have different tastes at the moment. She likes cute and pink fashion while I prefer down to earth style."