Damn I feel old reading this thread. Being a Parent myself I think its great to approach parents with music and the fact that your willing to do so should appease them, even if they don't like it. I've been listening to all sorts of metal music for many years, and I'm into it now more than ever. I would only say to enjoy metal for the power, intensity, rush the music can give you and not necessarily the content . Meaning, Mom might not like the songs that talk about murder, suicide, war, but explain to her that if the lyrical content was removed completely, its the music that still moves ya!
Have recently taken my son (lucky bastard) to his first few concerts, being the bands I grew up listening to, Maiden, Priest, Queensryche. We talk music alot even if we don't share the same tastes. Can't say that I listen to death-core growly metal as much as some here but I'm into thrash, epic/power, symphonic metal. Thats the great thing about metal, there are so many good styles and bands. Probably the reason I'm into it more now.