I know it won’t work but here goes.
Couple of hundred years ago, around 50% of children died before they were 5. But people had no contraception and lots of children so your immune system worked well enough, because enough people lived. Evolution doesn’t ‘care’. Enough people live, good enough. You might bury 5 children. But the human race continues. Group 1.
We developed vaccines, antibiotics, hygiene and other marvellous things, the child mortality rate goes down to single figures. Almost no smallpox, polio, TB it’s magically wonderful. Your children live. We develop contraception and you can have single figures of children and they will probably all make it. Group 2.
Do you want to be in group 1 or 2?
On causation and correlation.
Causation is when one thing CAUSES another. These can only be proved by scientific method. Typically double blind randomised control trials With a large enough sample size. This method is not perfect but it is the only way to prove something causes another thing without seeing the interaction first hand.
Correlation is when the prevalence of one thing rises and falls with another things but one doesn’t cause the other. For example, ice cream sales go up just before shark attacks. Ice cream sales and shark attacks are both caused by a third thing - sunny summer weather. Or things coincidentally rise together. Coincidences are really common and there are some fun ones on Spurious Correlations if you want to look.
You mate getting cancer, your cousin getting some virus, you getting MS. They may have happened just after a vaccine but you CANNOT say one caused the other. Not because you think it did, not because you googled something, not because you reckon. Any more than I buy an ice cream and some surfer gets bitten. Even though anecdata and correlation tells me it looks REALLY suspicious and coincidental. Life is coincidental.
Casting pearls before swine, I know.