Even your own excerpt doesn't say genetics for Elvis. Gladys had liver failure
"On August 14, 1958, Gladys Presley died, aged just 46.
The cause of death was a heart attack, and it was later discovered that one of the contributing factors was liver failure due to alcohol poisoning. "
Who was Elvis Presley's mother Gladys? The heartbreaking story behind her life and death - Smooth
I don't know anything about the others but you are quick to ignore anything else contributing so sorry if I'm not taking your assumption as concrete.
Also, I'm not arguing it's vaccine related. It could be substance abuse as well. We don't know.