We Don't Want To See Kim And Kourtney Feuding Anymore on 'The Kardashians'

Anyone with sisters can understand the sibling rivalry often portrayed on the reality series, The Kardashians. Besides five complicated female personalities, the dynamic of sibling birth order is in full effect with Kris Kardashian's brood. Medpsyche.net breaks down psychologist Frank Sulloway's infamous theory on how birth order affects personality traits. “Sulloway’s niche differentiation theory of birth order effects suggests that successive children are most different from the sibling preceding them in an attempt to be unique, and obtain attention, resources. etc. From this perspective, personality is a strategy that shapes how you interact with the world around you,” shares Dr. Catherine Salmon, professor of psychology at the University of Redlands and co-author of The Secret Power of Middle Children. “Birth order differences are thus shaped by differences in parental investment and the effects of sibling competition.”