Hiya
There's lots of good advice - I rather liked Jack's
For many, many young people there is a wall of sorts that exists between parents and their kids - it's as perennial as the grass and is only temporary from what I've seen and feel to be true from my own experience.
It may even be there when you've got kids, Gregor. You won't always understand them, they will hardly ever understand you The wheel always goes around. I believe even Socrates had a beef with the young people of his generation
What I've learned is that when people appear to be argumentative or difficult - or in any other way negative towards you, is to look for their 'intention' rather than their arguement or the words they use to express it. What lies behind them?
From where they view the world, your parent's 'intention' towards you isn't a bad one - they just want to see you get on in the only way they can perceive to be valuable. It isn't a valuation of you as a person - just a sort of worry that you aren't doing it in the way they understand. They don't intend any 'harm' towards you, and I'm pretty sure they love you dearly.
Otherwise they wouldn't give a monkey's what you did.
Step out of the confrontation for a bit and see if you can find their intention.