This 2017 German human study explored the relationship between birth stress and handedness. The authors summarized previous research which, among other points, estimated epigenetic contributions to handedness as great as 75%.

The research hypothesis itself was worthwhile based on the prior studies cited and elsewhere such as Group statistics don’t necessarily describe an individual. But the study hit a snag in its reliance on the sixty participants (average age 24) completing, with the assistance of their parents and medical records, a 24-item questionnaire of maternal health problems during pregnancy, substance use during pregnancy, and birth complications.

It’s extremely unlikely that the sixty subjects provided accurate information. For example:

• Only one of the subjects reported maternal alcohol use during pregnancy. An expected number would have been twenty-six!
• None of the subjects reported maternal mental illness during pregnancy. An expected number would have been at least seven!

I’d guess that the subjects’ parents willingly misled their children about facts of their child’s important earliest development periods. It’s my view that parental lies and omissions are not only unethical to the children, but also, whenever the lies and omissions became recognized, they potentially diminish or destroy the society among family members.

As mentioned on the Welcome page, lies and omissions ruin the standard scientific methodology of surveying parents and caregivers. The absence of reliable evidence made it impossible for the current study’s researchers to determine causes of epigenetic effects still present in the subjects’ lives.

Parental lies and omissions also diminish or destroy the society between the sources of information – the research subjects – and the users of the information. Such lies and omissions adversely affect anyone who values evidence-based research.

http://www.tandfonline.com/doi/full/10.1080/1357650X.2017.1377726 “DNA methylation in candidate genes for handedness predicts handedness direction” (not freely available)