Reply to Segal: Are relationships between birth weight and intelligence quotient variation within twin pairs modulated by patterns of handedness discordance?
Year: 2012
Type: letter
Abstract: We are grateful for Professor Segal’s interesting letter (1), prompting us to delve deeper into a question that was nested within, but not directly addressed by our recent article (2): Are relationships between birth weight (BW) and intelligence quotient (IQ) variation within twin pairs modulated by patterns of handedness discordance? In a sample of 67 monozygotic (MZ) twin pairs (of which ∼40% pairs were discordant for handedness), Professor Segal had found that lower IQ most often segregated with lower BW in handedness-discordant twin pairs when the left-handed member had the lower BW (3). This finding was argued to support two theoretical accounts for reported associations between twinning and left-handedness: the accompaniment of left-handedness by BW reduction relative to the right-handed cotwin [discordant left lighter (HDll)] indexing consequences of prenatal compromise, and left-handedness without BW reduction relative to the cotwin [discordant left heavier (HDlh)] potentially indexing the alternative mechanism of “delayed zygotic splitting and disrupted asymmetry determination” in twins.
Institution: National Institute of Mental Health
Language: English
Subfield: Cognitive Neuroscience
Field: Neuroscience
Domain: Life Sciences
Open Access status: green
OpenAlex ID: W2023753740