In his 2's, it must have been the private preschool he attended (with the overly priced uber expensive tuition):

In his 4's, it might have been his 1 year tenure in pre-K where he thrived academically and socially. Mrs. C pointed out that, "He has leadership qualities. All his friends listen and follow whatever he tells them to do" (a blessing and a curse). I think a lot had to do with Teacher Susan who prepared him academically in his after school kinder readiness class:
And while most of my mommy friends were sending their kids to fun-in-the-sun type summer camps Truman went to summer school at the Gifted Children's Association followed by pre-engineering Lego camp:
In his 5's, he became Leonardo's apprentice at Otis Art & Design College:
Truman said "Paleontologist" when I asked him what he wanted to be when he grew up. He could be the 41st since there are only 40 Paleontologist in the world.
But I like to give my kids options. I told him since he likes bones so much why not go to medical school to become a orthopedic surgeon...the seed has been planted.