YOU SAID:

If I get a cat then someone in my family has the possibility of getting an allergic reaction

INTO JAPANESE

猫を飼った場合、家族の誰かがアレルギー反応を起こす可能性があります

BACK INTO ENGLISH

If you have a cat, someone in your family may have an allergic reaction

INTO JAPANESE

猫を飼っている場合、家族の誰かがアレルギー反応を起こす可能性があります

BACK INTO ENGLISH

If you have a cat, someone in your family may have an allergic reaction