About 90% of the population is right-handed, which has often been proposed to result from a single gene. However, molecular studies rather support the idea that handedness is determined by a multitude of small, possibly interacting genetic and non-genetic influences. Here, scientists from the biopsychology lab, the genetic psychology lab and several departments of the medical faculty of Dokuz Eylül University in Izmir performed whole exome sequencing in nine left-handed members of a Turkish family with history of consanguinity in order to detect influences of rare mutations on handedness. Quantitative trait analysis revealed that rare variants on 49 loci on 26 genes show significant associations with handedness; however, none was functionally relevant for handedness (i.e. involved in left-right axis development or nervous system development). This interpretation was further supported by gene ontology analysis, as functional gene groups were also unrelated to the brain. Taken together, this study revealed no indication for a gene or mutation that could realistically determine handedness.

Ocklenburg S, Barutçuoğlu C, Özgören AÖ, Özgören M, Erdal E, Moser D, Schmitz J, Kumsta R, Güntürkün O. The Genetics of Asymmetry: Whole Exome Sequencing in a Consanguineous Turkish Family with an Overrepresentation of Left-Handedness. Symmetry 2017, 9, 66.