People who doesn't smoke but inhale it from other smoker is also affected. In fact, there are stories and topics regarding it. They get the same negative effects of cigarette just what the smoker himself will be getting. You can talk to your parents regarding it. They will surely understand you.
If you breathe in secondhand smoke, you are also taking into your system the nicotine and other toxic chemicals, thus, you are considered a passive smoker. This could result in having respiratory infections, severe and frequent asthma attacks, ear infections and Chronic cough. I advise you to keep away from people who smoke, to avoid secondhand smoke-related diseases.