As for the OP, I really don't know what will happen in your situation. Having an account opened longer than you've been alive seems impossible, but you never know.
Here is my story! I'm only sharing this so others are aware that Amex has, in the past, back dated new individual accounts to old AU account open dates. I can't be certain that Amex is still doing this tho.
I was an AU on my dad's Amex Platinum card in 1988. The account has since been closed and disappeared from EQ and TU reports (never reported on EX). In 12/06, I applied for an Amex Blue card in my own name (later converted to a Clear Card), and in 04/2007 I applied for a Gold Card in my own name. Some months later, maybe a year and a half later, I noticed when I checked my card accounts online, there was a message stating that I have been a card holder since 1988. I said, heck yes, baby!
I pulled all three of my reports and called the Amex credit bureau unit and asked them what the "open date" should be on these two accounts. They said 12/1988 for my Blue Card and 04/1988 for my platinum card. I told them the open dates on my reports for both cards was 12/2006 for my Blue and 04/2007 for my platinum card. They said that is incorrect. So, Amex sent me two letters, one for each card that clearly stated what the correct (well not really correct, but properly back dated) open date is. I sent a copy of each letter and disputed with the CRAs. Once the new open dates reported, my scores moved northward (especially on EX). It took some time, but it was well worth it. My length of credit history went from about 15 years to 20+ years, and IIRC, my AAoA nearly doubled.
Edited to add: all of this occurred in 2008
@GST2008 wrote:Hello All,
After talking with my father, I found out that he had an AMEX account way way way back in the early 70s (before he married my mother and was blessed with me lol). I know that AMEX backdates accounts, but would they back date that far (35 - 40 years)?
The second and more interesting question is, if he were to add me as an AU on that account, is it possible to have an account listed that is older than I am? I can only imagine what that would do to my AoAA.
1. Yes, if they still have him in their system, or he has his old account numbers/credit reports/receipts or something that shows he had an Amex back then, they will backdate. They've gotten A LOT tougher on backdating the past 1+ years if you're not already backdated in their system, though, so be prepared for that and talk to a supervisor to get it done.
2. Again, yes, if you're added as an AU on his backdated account, it will report on your credit with his opening date (1970's..), in spite of the trade line being older than you. There will be a notation on Experian that mentions something to the effect that your credit history is older than your Soc Sec #. That's about it. GO FOR IT!!!
Your actual card's "member since" date will show 2010; not the 1970s date that shows on your credit report, because that's when you are establishing a relationship with Amex. The two dates, in this case for an AU, are not connected, per se.
The above is based on 2010 experiences of at least 4 indivuals I'm aware of, so it should be the same for you. 
