You may not want your kids smoking or vaping but in the EU, is the Smoking Age 18 in the EU? If so, then nothing you as a parent to said LEGAL ADULT. You can talk to your adult offspring. Tell them to smoke outside because your house your rules. Let your kids grow up and learn life. Let them make mistakes. Some of those mistakes you are not going to like as a parent but you got to kick them from the nest so they can be functional adults themselves. Trust me, you'll have revenge when your kids have their own kids. Spoil them grandkids!!!!! DONT BE A HELICOPTER PARENT ALL YOUR KIDS LIVES!!!!!!