have no views of one's own 人云亦云

很多人容易受外在环境的裹挟，随波逐流，人云亦云。“人云亦云”，汉语成语，指没有主见，只会随声附和。可以翻译为“have no views of one's own，repeat what other says”。

例句：

他没有自己的主见，只会人云亦云。

He had no opinions of his own but simply followed the herd.