Star Birthmark

The Joestar birthmark appears in all people with Joestar blood as a star-shaped mark on the left side of the neck. Dio has the birthmark as well despite not being a Joestar on account of having grafted his head onto Jonathan Joestar's body. Because of this, all of Dio's biological sons have the birthmark. After inheriting Made in Heaven, Enrico Pucci and Weather Report also have these marks on their bodies, as the stand partially originated from Dio's bone and they are biologically brothers. In Part VIII: Jojolion, The protagonist's birthmark works as a part of his stand's ability.