@Ana1234 - Honestly, I would be very concerned about having other people on my internet, even if they are family. If something illegal is done on your internet connection, then you can be held liable for it, even if you aren't the one who did it.
This is the main reason people need to make absolutely sure that they secure their wi-fi so that no one can hack into it. There are people who basically drive around with their laptops looking for free connections so they can do whatever illegal things they want without getting caught.
I'm not super paranoid about it. I wouldn't really want to log every single thing that happens on my connection as long as it was secure, because I trust my family. But I also wouldn't give out the password to just anyone and I'd change it if there was any chance of it getting out.