2021-2022学年学英语报九年级第4期答案及试题

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Everyone has traits  that make us who we are. We have physical traits, like red hair, long legs and funny-looking toes. We also have character traits including humor, warmth, creativity and so on.

Certain physical traits are fully inherited (遗传), such as blue eyes and knobby knees. About genes (基因) are in a single cell in the human body. These genes carry the traits that are passed down genetically from parents to their children.

Many traits exist between inheritance and development — the interaction with environment. One example is body shape. It tends to be passed down from parents. But once diet becomes a factor, environment begins to play an important role in how the body develops. Body shape is a trait that is a mixture of inheritance from parents and influence of environment.

So lots of our most important traits have been learned, rather than inherited. For example, if you’re really great at video games, it’s not because your parents passed down the skills in genes. It’s because you have practiced a lot of video games and developed those skills yourself. If you have kids who turn out to be great at video games, it is because they put in the hours, learned the skills, and memorized the moves that are necessary to play the video games well.

Of course, some of us have brains that are more advantageous to video game playing. Say you were born with a large and powerful part of the brain that controls your hand-eye coordination.  That is inherited. What you do with it, how you choose to develop that advantage, is up to you.

You can pierce your nose or get a tattoo (纹身) — it doesn’t matter how much you change your body during the lifetime. None of those things will turn into genetic material to be passed down to the next generation. However, if your children grow up in an environment with role models who are pierced and covered in tattoos, they are more likely to get piercings and tattoos!