The spanking my mother tirelessly practiced really made my genes one of a well behaved kind.

 According to the latest research toddlers throwing tantrums is not a result of bad parenting but it is because of bad genes, New research into identical and non-identical twins suggests genetics have a more important role to play than previously thought.

For the past 25 years it has largely been thought that the development of childhood aggression was down to learning from bad role models.

Previous studies have indicated it starts during infancy and peaks between the ages of two and four.

However, scientists from the University of Montreal found there are substantial differences in both the frequency and rate of change in tantrums because of the 'interplay of genetic and environmental factors over time'.

‘The gene-environment analysis revealed that early genetic factors were pervasive in accounting for developmental trends, explaining most of the stability and change in physical aggression,’ said Dr Eric Lacourse at the university.

‘However, it should be emphasised that these genetic associations do not imply that the early trajectories of physical aggression are set and unchangeable.

‘Genetic factors can always interact with other factors from the environment in the causal chain explaining any behaviour.’

So just because children throw tantrums when they are small, there is no reason why they cannot be better behaved in later life.

The study, published in the journal Psychological Medicine, involved parents of twins born between April 1995 and December 1998 in Montreal, Canada.

It included genetically identical monozygotic twins who originated from the same embryo and non-identical dizogytic twins who developed in separate embryos.

Mothers were asked to rate the physical aggression of their twins by reporting behaviour such as hitting, biting, kicking and fighting, at the ages of 20, 32 and 50 months.

Dr Lacourse said that genetic factors explain a ‘substantial’ part of individual difference in physical aggression.

‘More generally, the limited role of shared environmental factors in physical aggression clashes with the results of studies of singletons in which many family or parent level factors were found to predict developmental trajectories of physical aggression during preschool.’

The results suggest that the effect of upbringing and parenting may not be as direct as was previously thought.

Long-term studies of physical aggression clearly show that most children, adolescent and adults eventually learn to use alternatives to physical aggression.

Dr Lacourse said: ‘Because early childhood propensities may evoke negative responses from parents and peers and consequently create contexts where the use of physical aggression is maintained and reinforced, early physical aggression needs to be dealt with care.

‘These cycles of aggression between children and siblings or parents, as well as between children and their peers, could support the development of chronic physical aggression.

My mother would straighten those genes with few belt strokes

The Daily mail