Why Do Men Kill Their Children?

Do men not care about their offspring? If you followed the Fritzl case, Mr. Fritzl's convicted and headed to jail for life (http://news.bbc.co.uk/2/hi/europe/7952275.stm). Too far from home? Consider a case from Alabama. One father threw four of his kids, 3 of which are his biological children, off a bridge (http://news.bbc.co.uk/2/hi/americas/7953646.stm). Isolated cases?