@Barry2021,
I will concede that you right on a small point. There is a very small chance that your sons visiting you will not being vaccinated will end with someone dying from covid. Scientifically speaking (and I accept all the science) that risk is
exceeding low, particularly for people in your household that are vaccinated. We can do the math if you want. I just looked up the numbers for Florida (which is what came up in my mind as a bad state, I don't know where you actually live).
For your sons to be a risk to you as a person
1) They have to actually have the virus. If they don't have the virus, they are no risk to you. From the numbers in florida right now, I estimate this risk is about 1 in 2100.
2) They have to transmit the virus to you. I looked up scientific papers, the risk that covid will be transmitted to an unprotected family member is under 15%. That brings the odds to about 1 in 14,000.
3) If you are vaccinated that dramatically reduces the chance you will get the virus. Assuming a 90% effectiveness rate, that brings your risk of catching the virus to 1 in 140,000.
4) Assuming your chance of getting covid is about 1 in 140,000 most cases of covid are minor. Only 1-5% of covid cases are fatal (and that number is even lower if you are vaccinated).
That makes the chance of you dying from your son's behavior is over 1 in 2,000,000.
Your actual personal risk is pretty damn low. Even at the height of the pandemic, heart disease and cancer are killing more Americans than cancer. If you are an older American, heart disease is far more likely to get you than covid.