Objective: According to the Lamarckism, some changes are occurred by environment on genes, then, acquired traits can be inherited. Today, epigenetic is the adjusted form of Lamarckism. Epigenetic points out to the expression of biological and characteristics factors in DNA. Based on the behavioral epigenetic, individual differences in personality and behavior can be resulted from fixation of acquired traits in genes. The aim of this study is to consider whether happiness and violence could be expressed in genes.   

Conclusion: Temperature traits such as happiness and violence are polygenic traits. Inheritance of these traits could be attributed to epigenetic mechanisms. According to the existing evidence in behavioral epigenetic, happiness and violence are acquired traits that could be referred to genes expressions by changes in environment. Therefore, these genes can be fixed and expressed in other newborns.