I looked into this, firstly by wondering do animals get shy?
Various responses I got from the internet ranged from personality, genetics and abuse, latter being that distrust and shyness inherently occur as a defensive reaction to the abuse from people.
Are shy and softly spoken people born shy or exposed to abusive behaviour that manifested into shyness? Are there trigger points, hereditary, learned.
Abnormal cortisol levels, affect on the cortisol system in childrens development. Abnormal stress hormones by listening to their parents.
[youtube="eYrQ0EhVCYA"] Chromatin, Histones & Cathepsin[/youtube]
Forms of 'soft' or epigenetic inheritance within organisms have been suggested as neo-Lamarckian in nature by such scientists as Eva Jablonka and Marion J. Lamb. In addition to 'hard' or genetic inheritance, involving the duplication of genetic material and its segregation during meiosis, there are other hereditary elements that pass into the germ cells also. These include things like methylation patterns in DNA and chromatin marks, both of which regulate the activity of genes. These are considered "Lamarckian" in the sense that they are responsive to environmental stimuli and can differentially affect gene expression adaptively, with phenotypic results that can persist for many generations in certain organisms. Although the reality of epigenetic inheritance is not doubted (as countless experiments have validated it), its significance to the evolutionary process is uncertain. Most neo-Darwinians consider epigenetic inheritance mechanisms to be little more than a specialized form of phenotypic plasticity, with no potential to introduce evolutionary novelty into a species lineage.