The 72nd Day

Do you know the twelve signs of the Chinese zodiac?
On Sunday, I went to dinner with people who were born in the year of the rabbit. 
There were people of the same age and 12 years old younger.
It was interesting that she distributed in a category of the Chinese zodiac. these sentences are not clear. please try to elaborate.



干支って知ってる？
日曜に、卯年の人たちが集まる会に参加した。
同じ歳の人と12歳年下の人がいた。
干支でカテゴリー分けするのがおもしろいとおもった。