User blog comment:Martialmaniac/Zzigg Zoldyck's fate?/@comment-24490201-20141106014148/@comment-5780397-20141108133326

So, you think Alluka was born naturally whereas Nanika came after Zzigg's expedition? Speaking in terms of timeline, the expediton took place many years before Alluka was born (probably even Silva was just a itch at the time). In this case, the second theory seems more logical to me.