User blog comment:IamJakuhoRaikoben/Sorcerer Magazine, Issue 30: June 2014/@comment-121.54.54.55-20140702083655/@comment-7418318-20140702112617

He certainly looks old enough to be over 100, but if Yuuri was Makarov's father, wouldn't we have seen some kind of reaction by Makarov when he heard about Yuuri's death?

Maybe an uncle or father in law or some other... less loved part of the family.