New research has found children who have been smacked by the age of three are at greater risk of experiencing poor mental health and behavioural problems up to the age of 14.
Published in the Child, Abuse and Neglect journal, the study analysed responses from more than 8,000 members of a longitudinal survey of 19,000 children born in the UK between 2000 to 2001 (known as the Millennium Cohort Study), where parents were asked how often they smacked their children and other discipline methods used.
Questions also included in the data were parental conflict, alcohol misuse and any existing psychiatric disorders. The collated data was then analysed against MCS data on behaviour and wellbeing of the children involved, including any emotional problems.
Two thirds of the children were found to have experienced at least one ACE by age three, while more than a fifth had had more than two. One in six had experienced three plus.
The most common of these were depression among their parents, 'harsh' parenting (shouting at/ignoring children), smacking, use of force between parents and alcohol misuse (parents).
Researchers also found boys were more likely to experience harsh parenting and smacking, however they found no significant difference in the mental health outcomes between genders.
Parental depression or conflict was found to be associated with 'internalising problems', such as anxiety in new situations, a lack of confidence and playing alone. These also increased as the child aged and in line with how many ACEs they had experienced.
While smacking or harsh parenting was associated with 'externalising problems', including poor mental health from childhood through adolescence.
Lead author Dr Leonardo Bevilacqua said there were 'stark links' between these discipline methods and adverse outcomes and parents needed to be educated on the long-term effects.
"It comes as no surprise that those children who have no or few adverse experiences as young children fare best of all and that those who have more negative experiences are more likely to behave antisocially and have poor mental health such as anxiety and depressive symptoms," he said.
"Our research, however, shows just how long those problems can persist at what is such an important and formative part of a young person's life."
The study builds on previous research from UCL which saw Scotland introduce a ban on smacking children in November, affording them the same protections against violence as adults.
Wales is looking to implement a similar law and researchers say the current study should inform a similar policy being introduced in England.