His siblings are in their twenties.

他的兄弟姐妹都是二十来岁。

Some studies have found that children are more friendly to younger siblings of the same sex.

一些研究发现，孩子们对兄弟姐妹中比自己小的同性更友好。

Sibling rivalry often causes parents anxieties.

手足之争经常让父母焦虑不安。