老师您好，我在阅读时读到一个句子感觉不是很理解。

You could have the traits that come with the gene but not the severity of problems that make it a “disorder.”

    1. 对于该句子，我知道 but not 起连接作用，但是无法确定句中 the severity 与 the gene 还是 the traits 并列。

    我看语法书上说平行结构中平行的两部分词性、结构应该相同。

    如果 the severity 与 the traits ，句中 the traits 后面是定语从句 that come with the gene ，而 the severity 后边是一个修饰它的介词短语 of problems  ，定语从句 that make it a “disorder.” 修饰的是 problems 而不是the severity。因此，这两部分结构好像不是很相同。

    如果  the severity 与 the gene 并列。我又做了一些思考，对于结构：

                名词1+ 并列连词+ 名词2 + 名词修饰成分（如定语从句等）。

    有没有可能出现“名词修饰成分”只修饰“名词2”这种情况，然后（名词2  + 名词修饰成分）作为一个整体与“名词1”并列。还是对于这种结构， “名词修饰成分”修饰的只能是（名词1 + 并列连词+名词2）这个整体。

   2. 该句中的 it 指代的是什么？

    恳请您不吝赐教。非常感谢！！！

附该句子所在的原文段落：

    Let’s say you do have the 7R allele of the DRD4 gene and you produce dopamine unevenly. You might also have other genes that mitigate its effects, such as those that influence serotonin production. Or your dad may have had the same gene and taught you at a young age how to deal with it, perhaps by his good example. Maybe you work in a setting that doesn’t require a lot of “farming” chores. You could have the traits that come with the gene but not the severity of problems that make it a “disorder.”(最后一句原文是斜体)

回答如下：

but not 这个分句实际上省略与前面句子相同的主语+谓语结构，如果补上去就是下面的句子。（在英语中，如果具有相同的主语和谓语，可以把后面的主语+谓语省略，从而达到使句子更加简洁的效果。）

You could have the traits that come with the gene but not the severity of problems that make it a “disorder.”

=You could have the traits that（定从） come with the gene, (but you could) not have the the severity of problems that（定从） make it a disorder

(句子语法结构：一个but引导并列句中有分别嵌套了2个定语从句结构）

主语+谓语+宾语(1)+that定语从句（1），+表示转折关系连词but+主语+谓语+宾语(2)+定语从句(2)

中文翻译：你可能会有随这个基因而来的一些特征，但是你不可能遭受因这些问题所产生的严重后果，这些问题会导致其功能紊乱.

继续回答如下

Let’s say you do have the 7R allele of the DRD4 gene and you produce dopamine unevenly. You might also have other genes that mitigate its effects, such as those that influence serotonin production. Or your dad may have had the same gene and taught you at a young age how to deal with it, perhaps by his good example. Maybe you work in a setting that doesn’t require a lot of “farming” chores. You could have the traits that come with the gene but not the severity of problems that make it a “disorder.”(最后一句原文是斜体)

中文意思：让我们说说，你身体里确实存在有DRD4基因的7R等位基因而且/因此你会产生不稳定的多巴胺，你身体也可能存在有其它的基因，这些基因可以缓和其影响，例如像那些影响羟色胺生成/产生的的基因或者说你爸爸身体里也存在有同样的基因并在早期就教你如何处理它，也许通过他的一个很好例子，也许你在一种不需要要求很多农场杂物工作环境下工作，你可能具有随基因而来的一些特征，但是你是不可能会遭受因这些问题造成严重后果，这些问题会使其功能紊乱.

备注：这里的it 指代the 7R allele of the DRD4 gene(DRD4基因的7R等位基因)

继续回答

Or your dad may have had the same gene and taught you at a young age how to deal with it 和这个句中最后一个单词it指代同一样事物it=(DRD4基因的7R等位基因)(另外，请仔细反复阅读其中文意思。）