A new study has been produced showing a link between smacking and aggression.
Experts did a survey of nearly 2,500 children in 20 large cities in the USA.
They found those who were regularly smacked at the age of three were more likely to be aggressive at the age of five.
The research is being published in the May issue of Pediatrics magazine.
Researchers also took into account other factors that could have made the children more aggressive.
These included physical and psychological abuse between parents and towards children, neglect, stress, substance abuse, depression and the consideration of abortion.
Even taking those factors into account, the researchers found children who were smacked three or more times in the month before the survey at the age of three, were 50 of adults thought it was acceptable to spank a child.
The evidence against smacking does seem to be stacking up. We reported on ParentDish last year that two studies had shown a connection between smacking and aggression.
But many parents defend their right to smack their children and mild smacking is allowed in the UK.
There have been calls for a total ban on smacking but so far any attempts to change the law have not been successful.
It seems you will always find plenty of people who say "I was smacked and it didn't do me any harm".
What do you think? Is it acceptable to smack children? Does it do them any damage?