[OPINION] Canada’s age-verification bill for porn is a slippery slope to a restrictive internet
(www.theglobeandmail.com)
Yes torrent and file-sharing in most cases violates copyright and is therefore illegal.
That fact won't stop people, especially teens, from doing it. But it is a fact.
As with most things involving kids, open, healthy and honest communication is the best way. If you don't have that then no constraints will really contain them, they will find a way around them, they will sneak around behind your back, and you will lose their trust.
Edit - I'm curious, do you believe it's acceptable to spank children?