Family patterns in handedness: Evidence for indirect inheritance mediated by birth stress

Abstract

The most common alternative to a genetic explanation of left-handedness is that sinistrality arises because of birth stress factors. In a sample of 1398 subjects, the association between birth stress and left-handedness was confirmed. More importantly, it was found that left-handed mothers are more likely to have birth-stressed offspring and that the presence of any left-handed sibling increases the likelihood of a history of birth stress in the proband. This was interpreted as suggesting that a plausible alternative to the genetic explanation for the usual pattern of association observed in family studies of handedness (where a left-handed mother increases the probability of left-handed offspring) is that the mother-offspring association may actually be mediated by birth stress rather than representing heritable aspects of handedness.

Is left-handedness associated with a more pronounced age-related cognitive decline?

“…This classification procedure of handedness is in 248 VAN DER ELST ET AL. agreement with recommendations made in the literature (Bryden, McManus & Bultman-Fleming, 1994;Coren, 1995;Porac & Friesen, 2000), but not all researchers may agree with this classification procedure. For this reason, we also evaluated whether using a trichotomous measure of handedness (sinistrals, ambidexters, and dextrals) rather than a dichotomous measure (sinistrals and dextrals) affected the results.…”

“…If fewer than eight of the ten questions were answered with ''left'' or ''right'', the respondent was considered to be ambidextrous. Ambidextrous people were included in the left-handed group in the present study, as is commonly done in other studies (Coren, 1995;Porac & Friesen, 2000).…”

“…theory'', a major cause of both sinistrality and minor abnormalities in the brain is hypothesised to be birth stress and prenatal complications such as a premature birth and low birth weight (Powls, Botting, Cooke, & Marlow, 1996), caesarean section (Coren, 1995), older age of the mother at the time of delivery (Coren, 1990), and smoking by the mother during pregnancy (Bakan, 1991).…”

Stress and laterality – The comparative perspective

“…While some studies at least partly supported the conclusion by Bakan et al [7], their results were often markedly weaker or only evident in subsamples (e.g. [22][23][24]60,83,102,119,124]). On the other hand, a considerable number of studies completely failed to find a relationship between birth stress and handedness [3,6,38,62,71,72,84,88,112,117].…”

Nongenetic Factors Associated with Human Handedness and Footedness in Japanese Twin Children

“…Familial left-handedness, including families with twin children, has been well established from research performed decades ago (19,(29)(30)(31). A clear association of parental handedness with the handedness of their children was observed by evaluating 25 studies on families (32).…”