A Victorian man raped his daughter almost daily for 30 years and fathered her four children in a case that echoes Austria's Fritzl incest horror, according to reports.

It reports all four children were born with birth defects in major Melbourne hospitals.

The victim's mother claims she was unaware of any abuse despite sharing a house with her daughter, husband and grandchildren until 2005.

Shocking story. It's amazing how this stuff can even happen. And what the hell drugs was the mother taking?

And The Age using a 'News Limited Newspaper' as a source? C'mon.

Surely would get sick of raping the same person nearly everyday for 30 years.

A+ for persistance.

And yeah, you really have to wonder how it could go on without anyone noticing :/