Parenting has zero influence on any psychological trait after age 21.
— Camus (@newstart_2024) August 11, 2026
Dr. Russell Barkley is direct about the data. Twin studies show parental influence peaks before age 7, drops sharply after that, sits at just 6% by the teenage years, and hits zero once someone turns 21.… pic.twitter.com/UA6BT5aYPY