Guys remember that there’s a big difference:

-Meteora’s marks are birthmarks and they have always been with her.

-Marco’s marks were created in that moment only because he’s using the Butterfly magic of the wand and his soul is bound with Star’s soul (that’s why it’s a moon, a reference of the Blood Moon). He even realized that when he touched the wand.  As soon as he stopped using magic, the marks dissapeared. 

So relax. They’re not blood-related or anything like that XD