Birthmark

A birthmark is a mark that appears upon a person at birth. In most people, they appear as some form of defect upon the person's skin.

In the EMPATH: The Luckiest Smurf story series, two known Smurfs of Empath's generation were born with birthmarks: Hefty and Empath. Hefty, being the first Smurf born of that generation, was given a heart-shaped mark that appeared on his right upper arm. Empath, born seven years later, was given a yellow star that appeared on his forehead. While very little is known about what the heart mark symbolizes, the star mark symbolizes the emergence of telepathic and telekinetic abilities within the Smurf who bears that mark.

Hefty would disguise the fact that he even had a birthmark at all by having Painter create an identical indelible mark on his left upper arm.