“家庭中的每一个人都很开心”翻译英文

仅从字面翻译的话，应该是：
Everyone in/of the family is happy. 或
Every family member is happy.

但是，我估计你是文章中具体用到的一句话，也就是说，应该有上下文的。那样的话，如果你前面已经提到了“family member”等类似词意的话，直接一个“Everyone of us is happy.”就搞定了。

Each and every single member of my family is happy.