While initially skeptical, Sam and Dean confirm Adam's identity through their father's journal and various "tests" (holy water and silver).

It is eventually revealed that the real Adam and his mother were killed and eaten by ghouls seeking revenge against John Winchester. The "Adam" Sam and Dean were interacting with was a ghoul that had taken his form and memories.

Dean is infuriated to learn John gave Adam a "normal" life—taking him to baseball games and teaching him poker—while he and Sam were raised as hunters.

In Supernatural Season 4, Episode 19, titled Sam and Dean Winchester discover they have a half-brother they never knew about. You can find episode details and community discussions on platforms like the Supernatural Wiki or IMDb . Episode Summary