Is it normal for obsessions to be quite to deeply linked

Note: this is neither trolling nor a fetish thing.

I have recently become fascinated with conjoined twins from an artistic and scientific point of view.

I have, throughout my life, had an obsession with the theme of duality.

Heaven and hell
Light and Dark
Manic and Depressive.

And I dont know whether this current interest is me trying to literally fuse my two polar opposites into one being.

I know its a litle weird, and no im probably not quite "all there"

but is it normal?