Exercise 1 — Left-handedness

LEFT-HANDEDNESS Roughly one person ¹ ten is left-handed. ² scientists have studied the question for decades, nobody knows exactly ³ causes it. It seems to run ⁴ families, which suggests that genes play a part, but identical twins do not always share the same writing hand. For centuries, left-handers had to put up ⁵ tools and furniture designed for the right-handed majority. Scissors, for instance, can be awkward to use, ⁶ can certain musical instruments. There may, ⁷, be real advantages to being left-handed. In sports such as tennis and boxing, left-handers often do surprisingly well, mainly because their opponents are far ⁸ used to facing them.