User blog comment:Stone Roger/Natsu and Zeref have somekind of relation?/@comment-125.212.121.11-20130610120525/@comment-7418318-20130610120922

People from Edolas (including Porlyuska and Mystogan) have no magic in their bodies and have to rely on magical items. When Zeref cast spells, he didn't appear to be using any magical items.

Furthermore there's the problem with Zeref's age. Porlyusca aged normally, like any other Human, but Zeref was born more than 400 years ago.