User blog comment:Twilight Despair 5/Fans for Season 8/@comment-3481504-20120408172318/@comment-3045936-20120408180553

I wouldn't know. Maybe a Nephilm is when a Angel possesing a human has a baby with another human. Maybe they are powerful and unlike all but the Archangels aren't connected to Heaven.

Angels also say they need human vessals to have sex as said by Anna to Dean on why she wanted to remain human, it never says that they cannot reproduce in their human vessals. Also, Anna is possible that Angels can be made sexual as her vessal she was born in by her human parnets after she removed her grace. It would make sense that the Angels would hate the Nephilm seeing them as abominations.