YOU SAID:

I have 2 sisters 3 brothers and 4 cousin

INTO JAPANESE

私は2人の姉妹が3人の兄弟と4人のいとこがいます

BACK INTO ENGLISH

I have two sisters and three brothers and four cousins

INTO JAPANESE

私は2人の姉妹と3人の兄弟と4人のいとこがいます

BACK INTO ENGLISH

I have two sisters, three brothers and four cousins

INTO JAPANESE

私は2人の姉妹、3人の兄弟と4人のいとこがいます

BACK INTO ENGLISH

I have two sisters, three brothers and four cousins