Both Eli and Peyton are protected by the football gods. It evens up the odds of being a great college and pro quarterback, yet having to endure what their father was forced to.
Their father, Archie Manning, a truly great quarterback, was doomed to a career with the New Orleans Saints during an era of probably the greatest futility for an NFL team in history and during a time in which free agency did not exist.
In his first six seasons, Manning and the saints won more than three games once. He made the Pro Bowl during their magical 78 and 79 seasons when their records were 7-9 and 8-8, the latter being the only non-losing season in Manning's career.
Keep in mind, this was before the quarterback friendly rule changes like "in the grasp" and head to head contact, and increased roughing the quarterback limitations. this guy got beat up every week.
Archie Manning suffered one of the worst fates for an elite college quarterback entering the NFL in history. He never participated in a playoff game. He went through five different Head coaches during his 11 years with the Saints. He never felt a shred of glory, for which the quality of his talent deserved.
It was so bad that his sons winning two Super Bowls each and remaining healthy actually evens the odds of being great quarterback and being screwed by terrible circumstances.