那么什么是人惯用左手如果它不是简单的遗传原因？
What then makes people left-handed if it is not simply genetic?
一些人有遗传原因倾向，有些是因为环境因素造成的。
Some people are genetically predisposed, while others lean toward depression because of environmental factors.
这一现象的遗传原因或许相对容易理解，但是社会对此的反应就复杂的多。
The genetic reason for this phenomenon may be relatively easy to understand but the society's response to it can be far more complicated.
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