Am I an idioit for this?

I took my cross bike to the mtb trail and my dad (who doesnt cycle or really know about bikes except how to fix certain things just because he is a very handy man.) chewed me out saying that bike was way to nice to be taking to the mtb trail and abusing. I always thought it was ok to do it. The bike should be able to handle it. The trails I went to were smooth. No drops or jumps that I had to take. So.... it is in fact OK to do this right?