Define the term "limb polarity" to mean things such as writing handedness, golf handedness, throwing ball arm preference and natural boxing hand. I avoid using the term "handedness" because of its limiting perspective usually limited to writing. In reality, there are many different kinds of handedness so many limb polarities. Learnt polarity such as ability to kick with both left/right foot is not the polarity: it is the natural skills such as coordination that make you use the other limb better than the other."
I find studies about handedness focusing only on writing handedness red herring: the thing is that there are many-many different kinds of handedness as well as footnedness. When reserchers focus only on writing handedness, they miss the large picture because every person has a lot of different handedness. The fact that you write with your right hand does not mean that you are right-handed in hockey or in other activity or play football with your right leg. I extend handedness now also to limbs such as legs and thumbs by the term limb polarity as defined above.
The below twin study data, now published, I think raises new questions.
What is the reason that the twins have the same handedness but their handedness differ in golf handedness? What determines limb polarity?
Should researchers focus on limb polarity instead of writing handedness in their studies?
Which genes determine the limb polarity in mammals?
Is there some academic term already used for the term limb polarity?
Twin Study Data
Assume identical twins with totally-matching handedness profiles
- writing: right VS right
- ice-hockey: left VS left
- football: right VS right
- baseball: left VS left
- tennis: right VS right
- throwing ball: right VS right
- golf: right VS left (ONLY DIFFERENCE known so far)
so limb polarity differs only in the last activity but otherwise the same. Why?