AuntieE
Doodledog
I’m be theory about Henry is that he suffered from Kell Syndrome. People who have it are affected in various ways, including psychotic episodes (which he had) and the inability to have more than one child with any partner. The sex doesn’t matter - sufferers can produce male or female babies, but after the first one maternal antibodies attack foetuses in utero. Catherine had Mary, so subsequent babies died or were miscarried. It was the same with Anne - after Elizabeth she couldn’t carry to term. Jane had Edward. She died soon afterwards, but would not have produced any more children if Henry did have Kell blood.
It’s an interesting theory, but is still unproven beyond doubt. There is evidence that at least one of Henry’s ancestors had the syndrome, which is hereditary, however, so it is a plausible hypothesis, and explains why he went from a fit, rational young man to an obese monster in older age - a situation that is often thought to be the result of a fall from a horse.
Actually, Mary was Catherine and Henry's first child to survive, not the first baby Catherine had, which makes it more difficult to find a medical reason for their lack of children.
Until I read that, I had wondered whether Henry could have been rhesus negative, but in that case, surely his parents would not have managed three children who survived infancy?
If after Mary's birth. he contracted syphillis or gonhorrhea that might account for the one baby per wife with Anne Boleyn and Jane Seymour, although Anne cannot have become sterile after Elizabeth's birth, as she is known to have miscarried about a year after having her daughter.
Apart from the age gap, Catherine's re-marriage to Henry or anyone else was delayed because both Henry VII and Ferdinand of Aragon were hard-headed businessmen. The one demanded the rest of Catherine's dowry, the other was reluctant and possibly unable to provide it, and probably felt that he could more profitably dispose of a daughter, still said to be virgan elsewhere that to England's new Prince of Wales.
That marriage also required a papal dispensation, never a particularly speedy matter, and certainly no need for haste when the putative bridegroom was only twelve.
I didn't discover the theory, and don't have enough knowledge of DNA (or even of more general biology) to argue a case. I read about it and found it interesting when I was researching Anne Boleyn some time ago, so offered it as a point of interest.
This is an AI overview, but there are a lot of more scholarly articles on Google Scholar that back up the AI summary of anyone wants to follow them up.