Editing Handedness (section)

=== Epigenetic markers ===

[[Twin study|Twin studies]] indicate that genetic factors explain 25% of the variance in handedness, and environmental factors the remaining 75%.<ref name="Medland">{{cite journal |last1=Medland |first1=Sarah E. |last2=Duffy |first2=David L. |last3=Wright |first3=Margaret J. |last4=Geffen |first4=Gina M. |last5=Martin |first5=Nicholas G. |date=1 February 2006 |title=Handedness in Twins: Joint Analysis of Data From 35 Samples |journal=Twin Research and Human Genetics |volume=9 |issue=1 |pages=46–53 |doi=10.1375/183242706776402885 |pmid=16611467 |s2cid=38843437 |doi-access=free}}</ref> While the molecular basis of handedness [[epigenetics]] is largely unclear, Ocklenburg et al. (2017) found that asymmetric [[DNA methylation|methylation]] of [[CpG site]]s plays a key role for [[gene expression]] asymmetries related to handedness.<ref name="Sun">{{cite journal |vauthors=Sun T, Collura RV, Ruvolo M, Walsh CA |date=July 2006 |title=Genomic and evolutionary analyses of asymmetrically expressed genes in human fetal left and right cerebral cortex |journal=Cerebral Cortex |volume=16 |issue=Suppl 1 |pages=i18-25 |doi=10.1093/cercor/bhk026 |pmid=16766703 |doi-access=free}}</ref><ref name="Ocklenburg">{{cite journal |display-authors=6 |vauthors=Ocklenburg S, Schmitz J, Moinfar Z, Moser D, Klose R, Lor S, Kunz G, Tegenthoff M, Faustmann P, Francks C, Epplen JT, Kumsta R, Güntürkün O |date=February 2017 |title=Epigenetic regulation of lateralized fetal spinal gene expression underlies hemispheric asymmetries |journal=eLife |volume=6 |doi=10.7554/eLife.22784 |pmc=5295814 |pmid=28145864 |doi-access=free}}</ref>