F Serpeloni et al. Transl Psychiatry 7 (8), e1202. 2017 Aug 15.

Changes in DNA methylation are postulated to underlie the transmission of stress-related effects from one generation to another. This Brazilian study of 121 families found that infants whose grandmothers had experienced significant stress during pregnancy also had evidence of DNA methylation changes.  These results prove that the effects of adversity can persist across as many as three generations.  Taking an intergenerational approach to prevention, it would also appear that improved management of perinatal stress can benefit more than one generation of children.

http://www.nature.com/tp/journal/v7/n8/full/tp2017153a.html?foxtrotcallback=true