All you would need to do is launch Wrye Bash and it should tell you which mod is doing it. I think Wrye Bash has an all-in-one installer now so no more downloading Python separately.
Otherwise, list your mods or buy DG.
I got it installed last night and was working on reading through the instructions to be sure I'm doing everything right. Looks like my best bet is to make sure all my mods are manually downloaded though, instead of the NMM auto-downloader? Anyway, then I got distracted by Terraria because I just had to try out the new content patch.
Also, apparently Steam users having the DG.esm was due to it being accidentally put up for free. If your Steam downloaded DG in that time you can still enable it without buying it, at least from what I've read.