YOU SAID:

the man does not mix with the boy who is a child which mixes with the father son cousin

INTO JAPANESE

男は父なる息子のいとこと混ざり合う子供である少年と混ざりません

BACK INTO ENGLISH

A man does not mix with a boy who is a child who mixes with his father's son's cousin

INTO JAPANESE

男は父親の息子のいとこと混ざり合う子供である男の子と混ざりません