-— I became an exchange student in France at the age of 17, where I lived with French families for a year and had a great horizon-expanding experience -—
You were fortunate. My girlfriend went to Germany, and the husband started hitting on her. She told the wife, who then became angry with her. She left the family in turmoil.
Girls shouldn’t live in the homes of strangers. It’s a recipe for disaster.
That is a rather uncommon and unfortunate circumstance. Normally, prospective families and students are interviewed, and only families with children around the students' ages are considered (at least, when I went back in the 1970s). The organizations who arrange these exchanges are very aware that people are entrusting them to keep their children safe.
I went with Youth For Understanding. It was a wonderful experience. I would hate to think that some teenager who has his or her heart set on experiencing another culture be told they couldn't, because their parents are too afraid something will happen. "Something" can happen anywhere, you can't live life in a state of terror because of the possibility.