I'm the mom of 4 teenagers, ages 17, 16 and 15 yr old twins. (God help me. ) For the most part, I trust them. However, if there seems to be a problem such as one of them becoming withdrawn, aggressive or something along those lines, I would most definitely snoop to see if I could find out the cause of the problem.

Otherwise, if everything is going well, I stay out of their stuff.