Your result, the one DNA position behind it, and what the research says.
5/10 confidence.
Roughly a tenth of people are left-handed, and it runs weakly in families, but handedness has been stubbornly hard to pin to genes. Very large studies have found dozens of positions, each nudging the odds slightly and none of them decisive. This is one of them. It sits in SLC39A8, which moves manganese and zinc into cells, and the same position turns up in many unrelated traits, so it is not a handedness gene so much as a busy one that handedness happens to touch.
Good to know: The odds ratio here is about 1.06, which is close to nothing. Identical twins are frequently not the same handedness, so much of this is not inherited. This position touches many unrelated traits, so it is not a handedness gene as such.
Fun fact: Handedness has been studied genetically for over a century and remains one of the least well explained common human differences.
Discovery: Common variants nudging handedness were found in very large population studies.
The single variant behind this trait
Gene: SLC39A8
Location: Chr 4:102,267,552
dbSNP rs13107325
Processing Speed: A change in an APOE intron linked to performance on a timed symbol-matching task.
Content updated September 2026.
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