Nor do I. I was into the goth subculture while it was still somewhat alive. Some things associated with BDSM could merge with goth and the reverse, but it isn't exactly so closely related. Many moms would have been even more hesitant to see their kids go goth!
As far as gothic gear goes, BDSM only really crosses over in a few small areas. As someone who's kinky and was once part of the goth subculture, they aren't really the same thing. Lingerie can be goth, books and movies can be goth (although I'm thinking more "Queen of the Damned" and less "When Someone You Love is Kinky" in the goth category), boots, clothes, and collars can be goth. But the rest of the kinky experience is Kinky, not Goth.