Oprah Winfrey (center), with the Kardashians clan
George Burns/Harpo Studios
06/14/2012 at 06:00 PM EDT
wanted to know: Was Kim Kardashian
's marriage to Kris Humphries a publicity stunt?
"This interview I'd say was another level of forthrightness and honesty," Winfrey writes on her Facebook page
."Why did she leave after 72 days? Her answer leveled me."
To prepare for her sitdown with the reality TV clan for this weekend's Oprah's Next Chapter
the talk show magnate "did a full on Kardashian Kram."
"I had never met them, nor seen the show," she writes.
Winfrey calls it the "longest interviewing session I can ever recall, talking to ALLLLLLLL the Kardashians."
"I genuinely wanted to know why they have become a cultural phenomenon? Why do so many people love to watch their every move and why do so many others love to hate them. Are they completely ego centered? Are they really 'famous for being famous' or is there something more?"
Oprah's Next Chapter
with the Kardashians airs Sunday at 8 p.m. ET/7 p.m. CT on OWN.