Researchers in Georgia studied a group of Rhesus monkeys who were abused and non abused as infants (both by natural or adoptive monkey moms) and found that while 9 of 16 of the abused infants grew to abuse their own offspring (whether abused by natural or adoptive mom), none of the 15 unabused infants abused their own offspring.
This is a pretty interesting study and is being correlated to cycles of abuse in humans. The only problem I see with such correlation is that while about 60% of the abused monkeys went on to abuse, current data shows that only 30% of human moms perpetuate the cycle.
It's still an interesting study... what are the implications here? If a human mom abuses her child should we place the child with adoptive (nonabusive) parents? Sure! I'm all for it.. unfortunately I'm not queen of the world, though, and what really happens is that the child is removed from the home (if they're lucky) and placed with family (if they're really lucky) or put into foster care where a great many of them are abused just as horribly as they were in their homes.
Am I saying we should just give up and not remove kids from abusive homes? Of course not! But it's really easy to say "take them out of the home!" and forget about it as a society... unfortunately its not nearly as easy as that.