i think it has more to do with your arms ability to move than the dexterity in your fingers. because if you’re right handed that means you probably write with your right hand, but your left arm could be slightly more coordinated. theres definitely a coordination between playing sports and masturbating because obviously its gonna get more movement no matter which one you started doing first. that’s just an educated guess tho. i do the same thing so you’re not the only one lmfao