Who am I? - Some riddle as a poem

Earth-born out of bloody love,
unsure, though, if this is true.
Above spans the old and rules
the sky in first generation.
Lots of children coming after,
some from mother, no from other.
Four sons were holding him together,
fifth taking what had made he man.

Who am I?

(First try writing a little poem-style riddle after reading a pretty interesting book. ^^)