Honestly, if you haven't taught your kids well and they enter their teenage and older years, they will be exposed to situations where they will have to make the "right" choice. You can't be there all the time, so you've gotta equip them with the ability to make the right decisions. If you are worried about a 13 year old making the right decisions, I think you screwed up not teaching them when they were younger.
These days parents forget about parenting and try to be their kids friend and all that. Once the child is an adult, you can have any sort of relationship you want, but through the formative years, you need to be a parent and a guiding light toward good.