Why is eating your boogers viewed as the most disgusting thing a person can do, when other things (especially sexual) that we do are much more disgusting but are widely accepted?

It's common knowledge that eating boogers is seen as disgusting. even just picking your nose is viewed poorly. But I'm curious as to why that is the case. I can understand it being bad if you don't wash your hands afterwards, because it would be like spitting on your hands then touching everything. But it's seemingly more acceptable to pick your nose, have a booger on your finger, and wipe it somewhere that eating it, which is more or less the equivalent of spitting.

But when you think about it, eating a booger is eating something that's made of your own mucus (which is always lining your throat), dust, blood, and bacteria, all of which is already inside your body. And eating your own boogers won't make you sick. Meanwhile, look at sexual acts. It's common practice and expected for you to give oral sex, getting another man's semen in your mouth, or getting the fluids from a woman's vagina in your mouth. It's become very commonplace to eat ass, licking the hole where someone's feces comes out of. And even just intercourse itself. All of these acts transmit diseases, literally called sexually transmitted diseases. You need to wear some physical protection to protect yourself from these diseases. But this is a common, normal, accepted social practice obviously, and you're even viewed as weird and wrong if you don't participate.

I'm just curious as to why eating your own boogers being reprehensible behavior came about if anyone knows.