I do not understand why と is incorrect when trying to say "both" [duplicate]

Question

Before I begin, this post is unrelated, despite the similar title.

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Here was the question:

My father and mother both are English teachers.

1. 父と母は英語の先生です。

2. 父も母も英語の先生です。

3. 父も母も英語先生です。

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I looked at each of the sentences and interpreted that

• 父 = ちち = father;

• 母 = はは = mother;

• 英語 = えいご = English; and

• 先生 = せんせい = teacher.

Therefore, Sentence 3 is incorrect because it is missing the particle の.

Now I also thought that

も = mo = also.

Thus, Sentence 2 is incorrect because there is no "also" in the italic sentence.

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So I circled Sentence 1 but I got the answer incorrect. Why so? What was the correct answer, and what does も mean when it appears twice in one sentence? Does the meaning change, or remain the same?

ありがとうございます。
Thank you in advance.

Answer 1

the key is 父も母も

XもYも is the Japanese way of expressing the idea of "both X and Y"