Handedness

Handedness is a variable between individuals that is determined by the number and severity of their hands. When two individuals are genetically identical, they have roughly the same number of hands. — Annoying machine

Handedness in the Bep universe diverges from that found in real life. Within the context of this universe, it is accepted that lateralization is a significant factor in handedness, among other things. All humans in the Bep universe are far less lateralized than their real-life counterparts. Thus it follows that they do not share our tendencies to handedness.

Terms used to describe handedness in the Bep universe:

• Being switch-handed involves being impurely ambidextrous, i.e. having the capability to do most or all tasks with either hand, but typically only using one at a time. It is often classified as ambidexterity, but without the coördination to use both hands at once. If ambidexterity means having independent hands, switch-handedness means having interchangeable hands.
• Being ambidextrous involves being able to use both hands for the same tasks independently. It is often classified as switch-handedness, but with the coördination to use both hands at once – and vice versa.
• Being switch-handed or ambidextrous with a biäs, i.e. left/right-switch-handed or left/right-ambidextrous, involves being able to do most or all tasks with either hand as with switch-handedness (interchangeable) and ambidexterity (independent), but having noticeable defaults for tasks or types of tasks. Cases of this sometimes arise from purely handed people adapting to using both hands. One might also describe this latter phenomenon as someone handed having trained switch-handedness/ambidexterity, but not having perfected it.
• Being purely right- or left-handed involves defaulting to one hand as dominant and one hand as secondary for all or most tasks. While this accounts for a majority of the real-world population, it is exceedingly rare in the Bep universe.

For brevity, the 7 main groupings of handedness are often lumped into 3 piles. True switches and ambidexters ("mixed"), biased switches and ambidexters ("mixed R/L"), and purely handed people ("pure R/L"). True switch-handers and ambidexters account for around 35% of the population, their biased counterparts around 60%, the remaining 5% being right/left-handed. Social factors contribute noticeably to these proportions locally. Societies that press ambidexterity, like the Bep, often see less than 5% purely handed (often leaving it near synonymous with people who've lost an arm) and a larger proportion of ambidexters. Societies that press dominant/secondary handedness often see up to 25% purely handed and a larger proportion of switch-handers. This means around 20% of the population is somewhere between pure and mixed handedness, swayed towards either by social and environmental factors. A further 45% of the population (10% biased mixed-handers, 35% pure mixed-handers) sway between ambidexterity and switch-handedness. In total, 65% of the population sways in some direction.

Ambi: 9%

Ambi/switch sway: 35%

Switch: 16%

Bias/mix sway: 10% (of which R: 7%, or which L: 3%)

Bias: 5% (of which R: 2%, of which L: 3%)

Bias/pure sway: 20% (of which R:9%, of which L: 11%)

Pure: 5% (of which R: 3%, of which L: 2%)