With just 10% of the population being left-handed, it can be easy for everyone else to forget we're living in a right-handed world. But aside from making it tough to cut a straight line with a pair of scissors designed for righties, being a southpaw can also have some subtle effects on our physical and mental health.

由于左撇子在人口中比例仅为10%，所以人们很容易忽略这样一个事实，即自己正生活在一个左撇子的世界。除了能够轻易地将自己同一般人区分开来之外，左撇子的习惯对个人的身体和心理健康还有着微妙的影响。

The brains and bodies of lefties may operate differently than those of right-handed people (and in mixed-handed people, who may have different dominant¹ hands for different tasks). "Handedness seems to be determined² very early on in fetal development, when a lot of other things about your future are being determined as well," says Ronald Yeo, PhD, professor of psychology³ at the University of Texas-Austin. Here's a look at some of the most common facts about being left-handed, and what it might really mean for your health.

习惯用右手的人，其大脑和身体的运转方式可能和左撇子有所不同 （对双撇子来说，不同任务中他们会习惯用不同的手。）“人的许多特点在胎儿时期就已经形成了，偏手性似乎也不例外，”德克萨斯州大学奥斯汀分校的心理学教授、博士罗纳德杨说。下面我们会探讨有关左撇子的一些常识以及左撇子对健康的影响。

It's not just genetics

左撇子不一定都是遗传因素导致的。

Scientists aren't exactly sure why some people are left-handed, but they know that genes⁴ are responsible about 25% of the time, says Yeo. Left-handedness does tend to run in families, he says, "but noticeably less than other inherited traits, like height or intelligence."

科学家们并不确定为什么有些人是左撇子，但是他们确信，左撇子的遗传因素占到25%。“左撇子的确会在家族内部遗传，但与体重和智力等其他遗传特性相比，其遗传几率却要小很多。”罗纳德杨教授说。

It's linked to stress in pregnancy⁵

左撇子与怀孕期间的压力有关。

In one British study, the fetuses⁶ of super-stressed pregnant women were more likely to touch their faces more with their left hands than their right. This could be the first signs of a left-handed child, say the researchers. Other evidence supports that theory. In one 2008 Swedish study of moms and their 5-year-old children, women who were depressed⁷ or stressed during their pregnancies⁸ were more likely to have mixed- or left-handed kids. In other studies, babies with low birth weight, or born to older mothers, were more likely to be lefties as well.

英国一项研究显示，压力较大的孕妇生出的孩子 更倾向于用左手摸脸。这可能是左撇子在婴幼儿时期的第一个征兆。而其他研究结果也证实了这一结论。2008年，瑞典的一项研究显示，孕期较为压抑或压力较大的妇女，她们的宝宝成为左撇子或双撇子的可能性更大。其他研究还显示，出生时体重较低的婴儿或高龄产妇生产的婴儿成为左撇子的几率更大。