Another source for John Rigby's age and his being single. Diocese of Shrewsbury website, Saint of the week, St. John Rigby
www.dioceseofshrewbury.org/weekly_digest/st-john-rigby-21st-juneIt recounts a conversation John Rigby had with the Earl of Rutland and Captain Whitlock on the way to Rigby's execution. They were " astonished that a man of 30 had found the strength to remain chaste" Then follows a description of the execution. After only a few moments hanging, Rigby was cut down: " A young and healthy man ...stood upright on his feet, startled but fully conscious." He remained fully conscious whilst being disembowelled; several men had to hold him down, one with a foot on his neck. ( So he was still fairly fit, although he'd been tortured in prison.)
So, if he died aged around 30, birth year about 1570 is correct.
He was raised a Catholic; his father, Nicholas was lapsed/ wavering/ conforming at the time of John's return to the R. C. faith. There might not have been a baptism record for John. He may have been baptised privately/ secretly at home. He may have had another christening at the parish church to make it seem the family were conforming.
There is an online family tree of Saint John Rigby (Geni Family Tree). This has given him a wife, Jane Bannister with an approximate birth year of 1595. If that date is correct she was only 5 when her husband died.
It also made her a few years younger than both children of the couple.
Going back a few generations in the same tree, a grandmother appears to have married 2 men named Nicholas Rigby, who both died the same year, one in his late 90s.
The other had a son only 10 years younger than him.
Forward a few generations and the alleged son of St. John Rigby (the son who was 2 years older than his ma) had 7 children in 6 years with his wife, which seemed to include 2 sets of twins. (Possible). The tree does have the correct parents of St. John Rigby.