One may be unable to control the emotions that one feels regarding a particular issue once that person has made a determination regarding how he feels about that issue. However, that emotion is based upon the thoughts and moral opinions regarding similar events or ideas leading up to that point. The person does have control over whether or not he objects to something or not, at least in the days and years leading up to it. One may choose whether or not he agrees with getting vaccinations, for example, years before he is confronted with a situation when that opinion comes into play. He then might become upset if he is confronted with someone getting vaccinated, and may not have control over his emotion, however he did have control over whether or not he agreed with vaccinations in the first place. That is, if we have free will at all. Feeling an unwanted emotion and taking appropriate, or no action IS mature. However the original emotion is a result of immature mental planning and mental preparation. If the person had prepared himself for all contingencies then they wouldn't feel any unwanted emotion to begin with.

I'll put it this way. If I decided right from birth that everything I experience is a good thing and that nothing could ever bother me, then I would be very happy for the short time that I lived.

In this particular case a person is wrestling with jealousy that has occurred because he decided before now that this is the appropriate reaction for him. I respect his freedom to feel jealous about this as long as he respects my freedom to see that as a sign of immaturity. That doesn't mean that it is. It just means that this is the way I see it. It holds no logic. There is no good argument to support it, and it holds NO consideration for others. Not just ANY others, but those he holds close. I see it as selfish, and that is my fault. I accept responsibility for that because my opinion is based upon the moral decisions I have made leading up to this point.