The researchers looked at people aged between 13 and 77 who had completed interviews about their work, personality, and family lives, which psychologists and psychiatrists then analysed and ranked on a scale from 1 to 5 - with 5 having the most narcissistic traits like defensiveness, authoritativeness, and stubbornness, and 1 having the least.
They used "hypersensitivity" to determine a person's level of defensiveness.
William Chopik, a social-personality psychologist at Michigan State and a co-author of the study, explained that the experts defined it as being unreceptive to others' feedback and lashing out at any criticism toward one's self.
They found that, overall, younger generations are less hypersensitive than older generations.
The millennial generation, which includes people who are currently between 23 and 38 years old, is less sensitive than the baby boomer generation, which includes people between the ages of 55 and 73.
The good news is that people get less narcissistic as they get older, according to the results of the study.
In fact, the researchers found that hypersensitivity sharply declines after the age of 40.
However, the look into the generation-specific trends still confirmed that difference between baby boomers and millennials.
Chopik attributes this contrast to generation-specific events that shaped the participants' outlooks on life.
For example, in the US, Chopik explained that "baby boomers may be more narcissistic than other generations because they grew up in a time when the government provided privileges like social security".
Chopik did note that narcissism levels can be measured in different ways so different studies could show different results.
"Based on our study, there's weak evidence that this [younger] generation is the worst in human history," Chopik said.
"We know younger people on average are more narcissistic, but that goes away as they age. People will live their own lives and have experiences to lower that narcissism and mature," he added.