The BBC America cult hit series Orphan Black has fast-paced plotting and amazing acting, but it’s something more psychological that keeps viewers hooked.

I thank Doctor Who for introducing me to Orphan Black. A couple of years ago, BBC America aired Doctor Who at 9 pm. When 10 came around, I was too lazy to lift the remote and change the channel, so I left it on. The next show? A new Canadian-produced sci-fi show with the weird title of Orphan Black. It only took one episode to hook me.

The premise: Sarah Manning, a rough-around-the-edges London transplant living in Canada discovers by chance that she’s a clone. Together with fellow clones Alison, an uptight soccer mom, Cosima, a gay, hipster science nerd, and Sarah’s loyal foster brother Felix, she tries to unravel the mystery of her existence, while protecting herself and her young daughter, from sinister forces.

Orphan Black, if you haven’t guessed, is not your standard thriller.

What makes this show great is, first and foremost, the top-notch writing. Orphan Black moves at breakneck speed (sometimes too fast). Once it has you, it doesn’t let go. And it is unflinching in its violence.

And then there’s Tatiana Maslany. This actor is amazing. She plays each of the clones (I read that there’s been 12 accounted for, but we’ve only seen 9. Maslany has played all 9. Even when it’s just a brief portrayal, Maslany manages to impart a unique persona on each clone.

Often, though, the clones interact with each other in a single scene. Think about it: one actor playing 3 different parts in a five minute scene. She does more than just pull it off. We quickly forget that it’s only one actor who we’re seeing. And then there was the scene where Maslany played Alison impersonating Sarah. Brilliant.

But to me the secret appeal of Orphan Black lies in its premise: clones. Clones are really nothing more than identical twins — two (or more) genetically identical humans. But identical twins, while they share the same exact DNA, are often more dissimilar personality-wise than alike. The same with the clones in Orphan Black. You have clones ranging from rough-edged transgender Tony to the corporate ice queen Rachel. Genetics doesn’t equal destiny.

What Orphan Black gives us, on an unconscious level, is a “what if” moment. What if I’d been born rich/poor/unwanted/loved? What if I went to/never went to college? What if I got married/never got married? We all have lives that go unlived, even those of us who live to the max. Choices inevitably are made. In Orphan Black, we get to see one genetic code across a range of lives and situations and choices. Why is Sarah straight and Cosima gay? Why is Alison so uptight while Sarah is so free-wheeling?

Who knows? But playing along in this game is half the fun.