Celebrity Parents Bottle-Fed Infants Are More Likely to Be Left-Handed Than Breastfed Babies, New Study Finds "We think breastfeeding optimizes the process the brain undergoes when solidifying handedness," said University of Washington study author Philippe Hujoel By Jen Juneau Jen Juneau Twitter Jen Juneau is a digital news writer for PEOPLE. A '90s teen and horror film connoisseur, she started at the brand in 2016, after a decade of working as a technical writer and then moonlighting as a journalist beginning in 2013. Originally from New Orleans, Jen grew up both in NOLA and Florida and eventually attended the University of Central Florida in Orlando (still her home base!), where she earned a bachelor's in English/technical communication, with a minor in magazine journalism. People Editorial Guidelines Published on January 9, 2019 05:00 PM Share Tweet Pin Email Photo: Miguel Sanz/Getty New research suggests that people are more likely to become left-handed or ambidextrous in adolescence and adulthood if they are fed from a bottle as an infant. The findings, extracted from a study conducted at the University of Washington that was published last month in the scientific journal Laterality: Asymmetries of Body, Brain and Cognition, were based on a group of 60,000 pairs of mothers and children who breastfed or bottle-fed their babies. Specifically, the study found that babies who breastfed for one month had a 9 percent lower chance of being non-right-handed, while one to six months showed a decrease of 15 percent and more than six months had a 22 percent lower chance of “nonrighthandedness.” Want all the latest pregnancy and birth announcements, plus celebrity mom blogs? Click here to get those and more in the PEOPLE Parents newsletter. Getty Mom Endures Painful Breast Infection, Surgery to Continue Nursing Son According to Science Daily, the author of the study — Philippe Hujoel, an adjunct professor of epidemiology at UW’s School of Public Health and professor at its School of Dentistry — said, “We think breastfeeding optimizes the process the brain undergoes when solidifying handedness.” The conclusion also shed light on how long a mother would need to breastfeed before it had any kind of lasting impact on the brain’s development in terms of whether a child would be right-handed or not — with over six months, as mentioned previously, having the largest impact. “It provides an independent line of evidence that breastfeeding may need to last six to nine months,” Hujoel explained of the findings, according to Science Daily. (However, “Breastfeeding infants after nine months was no longer associated with further reductions in the prevalence of nonrighthandedness,” the study concluded in part.) RELATED VIDEO: Southern Charm‘s Cameran Eubanks on Why She Stopped Breastfeeding: “I’m Just Plain OVER IT” Hujoel clarified, according to Science Daily, that the method of feeding only suggests an in-part link between itself and handedness, while much of the latter is determined early in the fetal stage. Instead, feeding may influence handedness during brain lateralization — a later process Science Daily describes as “when the region of the brain that controls handedness localizes to one side of the brain.” Thus, “It is concluded that the critical age window for establishing hemispheric dominance in handedness includes the first nine months of infancy and is in part determined by nurture,” the study said.