'I will strongly advise parents to seek expert advice and help and to carefully watch out on the best practices to handle their sinistral (left-handed) children,'' he said.
Afolabi, who is also a sinistral (left-handed person), said he had it tough while growing up as he was forced switched to write with his right hand in school.
This suggests that maternal, rather than paternal sinistrality, is associated with the elevated incidence of left-handed sons issuing from LL couples, the generally higher incidence of left-handed sons to LL couples possibly, therefore, being due to maternal sinistrality plus a minor base rate increment attributable to either dextral or sinistral fathers.
In the present sample left-handed mothers produced the highest incidence of sinistral sons and left-handed fathers produced the lowest incidence of sinistral sons, the rate for the latter being no different than that for right-handed fathers.
The sample did not, however, show a significantly greater incidence of sinistral sons than sinistral daughters born to LR couples, and Risch and Pringle did not point out that any of their findings might be considered to be consistent with X-linkage.
It seems her interpretation of the results is that there is a heterozygote advantage that accounts for the superiority of class 4 dextral males, but a specific superiority of the rs- - genotype among sinistral males, who scored higher than class 4 males.
The results for the spelling test showed superior performance of the most dextral individuals, poorest performance of the most sinistral, and intermediate performance by the groups with intermediate dextrality.
The decision to study only dextral persons was taken when we realized the difficulty and time vista required for securing adequate numbers of male and female volunteers to constitute adequate samples of the three sinistral hand preference classes in Annett's hand preference procedure.
The most sinistral (group 1) included probands with differences in favour of the left hand, 20.6 per cent and a further 4.4 per cent with no differences between the hands or with a marginal difference in favour of the right hand.
The relations between spelling and educational success on the one hand, and hand skill differences on the other hand, take the form of linear trends reflecting lower abilities for the most sinistral group and superior abilities for strong right handers.