Mutate!

 is a Fallout, Fallout 2 and Fallout Tactics perk.

The radiation of the wasteland has changed you! One of your Traits has mutated into something else... Notes:
 * If you chose only one Trait when creating the character, you can only exchange it for a new one. You cannot fill the empty slot.
 * In unpatched Fallout 1, you could exchange Gifted for another Trait and still keep the Character Points.

See also: Mutations and their causes.