YOU SAID:

peter looks like his sister

INTO JAPANESE

ピーターは彼の妹のように見えます

BACK INTO ENGLISH

Peter looks like his sister

INTO JAPANESE

ピーターは姉のように見えます

BACK INTO ENGLISH

Peter looks like an older sister

INTO JAPANESE

ピーターは姉のようです

BACK INTO ENGLISH

Peter seems to be my sister

INTO JAPANESE

ピーターは私の妹のようです

BACK INTO ENGLISH

Peter seems to be my sister