Trait and state alexithymia
I only figured out I'm autistic in 2022. I'm still learning. Writing these articles is how I learn things. They're all works in progress, to various extents. No-one can speak for an entire minority group. These are just my personal experiences, things I've found out from talking to my friends, and discussions I've seen on autistic forums. Please don't take me as authoritative. I'm not.
I was born this way
— Lady Gaga, "Born This Way", 2011
Trait and state alexithymia (also known as primary and secondary alexithymia) are, respectively, permanent and temporary alexithymia.
For the purposes of this article, I'll be talking about affective alexithymia in particular.
Some people were simply born without the ability to feel emotions unless they're extremely strong. I believe this is what applies to me, for example. It's likely an extension of interoceptive hyposensitivity, and is quite common amongst autistic people such as myself. (You can't feel your gut telling you you're in trouble if you can't even feel it telling you you're hungry.) This is a neurological cause that can't be changed, it's just how and who you are. The best you can do is develop some workarounds and try not to worry about it too much.
In contrast, people who experience trauma may develop temporary alexithymia as a defence mechanism. This is a psychological issue rather than a neurological one, and there are apparently psychological therapies that can help alleviate or fix it. I gather people tend to get really freaked out at suddenly developing alexithymia, in much the same way you might get really freaked out at suddenly becoming blind, and indeed, it's something to look into with a doctor immediately.
But as someone who was very likely born this way (although it's impossible to rule out largely forgotten childhood trauma being an influence), it personally doesn't bother me all that much... I assume.
Alexithymia: Affective alexithymia | Trait and state alexithymia