>What makes you think people can't, in at least some cases, control their emotional responses?

So, is your assertion then that sometimes Free Will exists and sometimes it doesn't? Seems to me it's a rather binary proposition, I mean if you can exert free will in some cases, why not others? Does the severity of the stimulus affect whether or not you have free will, and therefore the ability to choose your emotional response?

As to what makes me believe that people cannot, in any circumstance, control their emotional response.

Well that's based on 40 years of observation. And a recognition that almost everyone else's emotional responses work relatively similar to my own. That, coupled with being able to formulate hypothetical scenarios which explicitly lay bare the notion that you cannot, in fact, choose your emotional response to any stimuli.

Consider this...

You are at the park rolling around a ball with your most favorite precious little puppy whom you love dearly. You adopted this puppy from a shelter and you and this puppy share a deep emotional bond.

Now,

 Scenario 1 - a man walks by, looks at the puppy, looks at you, then leans down scoops up the puppy carefully holds it against his chest, scratches behind it's ear, then gently sets the puppy back down and continues on his way.

Ultimately, this is a fairly innocuous event. However, you most definitely experienced some emotional response to this event. Perhaps, beer, because you did not know this man's intentions and whether or not he was just going harm your puppy or just walk away with it. Perhaps you experienced happiness, because you assumed that he was doing the very thing he ended up doing and you find it pleaseing that someone else finds your puppy adorable, so you experience some amount of Joy or happiness.

 Scenario 2 - a man walks by, looks at you, looks at the puppy, then proceeds to kick the puppy like a football, looks you straight in the eye, truffles and walks away.

.. An absolutely horrific event. To which you most definitely have an emotional response. Great, anger, abject horror...

Now, in either of these scenarios, did you choose your emotional response? Could you choose to respond to scenario two with joy and happiness? Could you choose to respond to scenario one with absolute furious anger? To be sure, depending on your ability you could outwardly act in a seemingly incongruent manner. But that still would not change the fact that inwardly you had an emotional experience beyond your control. And even in scenario one, we could add additional background information which would alter the most likely expected emotional responses. And these would be the things that influence any given emotional response to any given event you witness no matter how innocuous or impactful it is.

And in the same way in which those previous experiences and your current state of mind dictate the emotional response you will experience, so too does previous experience and current state of mind dictate any action you will or will not take when experiencing any given emotional response.

The emotional response, the action you do or don't take based on that emotional response, very act of having an inner dialogue weighing out potential benefits and outcomes of various courses of action, all these things are beyond your active control. They're all the results of your brains current condition. We can even see this cases of people who experience head trauma. When the rain experiences literal physical alteration it can completely alter someone's personality. And they cannot simply choose to behave in the way they did prior. Their behavior, and thus there responses and actions to the world around them are entirely dictated by the physical composition of their brain which is intern manufactured by all previous experiences.

All these things occur beyond your control and interact in such a way so as to make you feel as though you are actively making these decisions. To be sure, it is a very strong illusion, but it is an illusion nonetheless. Elsewise you may as well be a radio that believes itself to be the world's greatest musician simply because it receives a stimulus processes said stimulus through available circuitry and then generate output based on that processed stimuli.

(Please be assured that no cute little fluffer puppers we're actually harmed in the formulation of these hypothetical scenarios, though unfortunately, neither did any cute little puppers receive ear skritches)

As for the second part of your comment, I'm not so sure anything I've said should have implied that I believe that any of this is removing the "I" from the system. Merely pointing out that human experience is comprised of interconnected identities, however pointing out that neither of which is an "I" that can choose, through free will, to act with disregard the physical composition and current state of mind which it emanates from.

Yes, but we need to believe that "selves" can be controlled otherwise how could we enact laws and operate as a society?