Young men under the age of 25 do not have a fully developed brain which would include impulse control and rational decision making.
Mass school shooters under the age of 21 in Newtown, CT; Columbine, CO; Parkland, FL; and Uvalde, TX.
Reference: New York Times
87
Since 2018, the deadliest shootings in our country were committed by men who were 21 or younger.