Differences in the temperament of puppies depend on the genome, scientists from the University of California have found. The researchers' work was published in the journal Frontiers in Psychology.

Epigenome screening can show whether a puppy will be energetic or fearful. The epigenome is a kind of regulatory layer located as if above the genome. It regulates which genes should work and which should not.

A dog's epigenome depends on age, diet, exercise, training, socialization and other environmental factors, and it can affect nerve cell activity and conduction and thus change behavior.

The researchers quantified epigenetic, genetic and behavioral differences between 46 females and males of 31 different breeds between the ages of one and 16.

Behavioral differences were determined based on how owners completed a questionnaire. The researchers then examined the epigenome. The results showed that two of the 930 single-locus polymorphisms (SNPs) selected were strongly associated with behavioral traits. They could partially predict the degree of a dog's fear of strangers. The scientists will continue the research in the future.