Star Birthmark

The Joestar Birthmark (ジョースター母斑) is a clearly five-pointed star-shaped mark appearing in the region of the rear of the left shoulder on all JoJos or individuals of or in certain ways connected to the Joestar bloodline.

Introduced in Part III: Stardust Crusaders, having stolen Jonathan Joestar's body, Dio receives this birthmark. Fathered after this theft, all of Dio's sons also bear the mark, including Giorno Giovanna.

In Part VI: Stone Ocean, after inheriting Made in Heaven, Enrico Pucci and Weather Report also recieve the mark, as the Stand partially originated with Dio's Bone; and as brothers, they connect and affect one another in the same way Dio does Joseph, Holy and Jotaro in Part III. Once Emporio Alnino enters the new universe, he discovers that Irene possesses the mark, helping him identify Jolyne as surviving in a new form.

As JoJos, Joestars or members of Dio's progeny, it may be assumed that George Joestar I, George Joestar II, Josuke Higashikata, Donatello Versace and Johnny Joestar have the birthmark as well.

In the new universe of Part VIII: JoJolion, the protagonist's birthmark factors in his Stand ability, and it is eventually revealed that Holy Joestar-Kira, Yoshikage Kira, Kyo Nijimura, and Josefumi Kujo, descendants of a new Joestar line, also possess it.