User blog comment:Miskos3/Fairy Tail 525: Why Did the Emperor Never Love His Child?, Review/@comment-5303512-20170304145630/@comment-1776824-20170304233255

Or...Larcade implied that he was created artificially (like Natsu), and thus he was born, quite literally, through love (or "magic" as the series likes to call it), and people are taking Larcade's magic affecting Mavis and Zeref (the latter of whom does not have the body of a 13 year old, but of a young adult) too far into account. Zeref is 400+ years old. Dude probably fucked someone. 10 years between 0 and Zervis flashback. She was an adult, probably had sex too. It's explained right away if you give it some thought, though I will admit that at first, I thought he plowed a corpse too.