In Brazil, your ISP, according to the law, must keep a track of the connections you do with your IP address from your network. This track is used to prove that "you" (or someone using your WiFi, or some virus, or someone who infected you with a Trojan, or someone with a laptop in those conditions that used it in your home, but, for our law, "you") did something in your network, when someone breaks the law and there's an IP record of the source.
So, what if someone uses Tor for sharing, e.g., kid's porn, and some file transfer happens by your network's node? Would you be in trouble? Is there any way to avoid that?