作者的弟弟英文翻译为"author's younger brother"。

这个词的来源是由两个单词组成的："author"和"younger brother"。"Author"是指一个写作者，而"younger brother"则指比作者年长一些的弟弟。

下面是一些英文例句及其中文翻译：

The author's younger brother is a successful businessman.
作者的弟弟是一位成功的商人。
The author's younger brother was always a handful when they were growing up.
在作者们成长的过程中，作者的弟弟总是个麻烦。
The author's younger brother has always been supportive of his writing career.
作者的弟弟一直支持他的写作生涯。