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Such societal and environmental theories of handedness go back at least to the time of Plato in Ancient Greece. Plato was convinced that the limbs are naturally of equal strength and ability, and that any handedness is culturally imparted. In fact, he went so far as to blame left-handedness on inept mothers and nurses who failed to adequately school their children in the correct way of doing things.
In modern times, societal theories became particularly popular through the work of the influential American psychoanalyst Abram Blau in the late 1940s. Blau was a confirmed behaviourist, who explicitly attributed handedness to environmental factors alone, asserting that it is purely a product of a child�s culture and upbringing, and denying any genetic or biological influence at all. In spite of his own research, which signally failed to confirm his theories and predictions, Blau characterized left-handers as perverse, stubborn and rebellious, and blamed the persistence of left-handedness on cold and loveless mothers.
Such theories assume that societal and environmental pressures can dominate over any genetic or biological tendencies - that nurture wins over nature - and also that handedness is in fact a behaviour, which can be taught and learned like other behaviours. The statistics around left-handedness in countries where there is strong social pressure to adhere to right-handed norms (e.g. Taiwan, China, Japan), and where left-handedness is in fact dramatically lower than in the more permissive Western countries, suggest that this is indeed the case, at least to some extent.
But it is by no means certain that handedness can be dictated by parental and societal behaviour and practices. For instance, John Santrock, in his 2008 book Motor, Sensory and Perceptual Development, reports that the handedness of adopted children is actually more likely to be related to that of their biological parents than that of their adoptive parents, which suggests that handedness may not in fact be taught by parental role models, but must have at least a genetic component. Additionally, nearly 20% of identical twins, who are presumably brought up in a very similar way, have been shown to have different hand preferences.
Another, more indirect, societal influences on handedness is the very language we use. Many words and phrases in many different languages carry positive connotations for �right� and negative connotations for �left�, and many of the colloquial phrases used to describe left-handedness (such as �buck-fisted�, cack-handed�, �caggy�, �spuddy-handed�, �squiffy�) are similarly uncomplimentary, and carry with them derogatory connotations. More details of the way handedness is used in language can be found in the section Handedness and Language.
While this obviously does not explain why a person might be naturally left-handed, it may go some way to explaining why a person might decide to switch or suppress their handedness. This was a much greater problem in past centuries (see particularly the section on the Recent History of Handedness), although it still continues today, even in the relatively enlightened West. By some estimates, 6-8% of right-handed Americans, particularly among older generations, are actually natural left-handers who have been forced (or at least encouraged) to switch at a young age (along with presumably an unknown number of others having switched before their memories reliably begin). Other studies suggest that 24% of younger generation left-handers have made at least some attempt to switch their own writing hands.
Although they have a certain amount of common-sense logic and anecdotal validity, these societal theories make no attempt to explain why the majority should be right-handed in the first place, nor why left-handedness has persisted so long in the face of such strong cultural pressure over the centuries. Neither do they explain why the handedness of adopted children tends to be more closely aligned with that of their biological parents than their adoptive parents.