what reasons would a couple not tell the child he/she is adopted until very late in life if at all? Know anyone in this situation?

Typically it is out of fear that the child won't love the parents as much if he or she knows about his or her adoption. This is not true, but some parents believed it.

Also, especially in which you and I were adopted, adoptive parents were told that infants were "blank slates" and that we would never want to know about nor search for our original families. It was a common theory at the time and parents were led to believe if they never mentioned it, it wouldn't ever matter.

While it is not common anymore to keep adoption a secret, it was fairly common in earlier generations. People really believed that adoptees would never want to search for their original families and agencies and lawyers were not careful about gathering background information. Some parents just chose to never tell, thinking that if being related through adoption it didn't matter to them, it wouldn't matter to the child.

DNA has allowed many adoptees like me to find our previously unfindable family members. If you are interested in searching, submitting your DNA to ancestry.com is a good first step.

I do not know anyone in this situation. Keeping adoptions secret from the children really went out of fashion in the 1950s and 60s.

Only reason I can think of to do that today would be if the father or mother was an infamous criminal, like Ted Bundy or Charles Manson, that maybe they'd be happier not knowing about.

You have to remember that there was a huge stigma attached to illegitimacy in earlier generations, and to a lesser extent there was a stigma about being infertile. It was probably assumed that no child would welcome the burden of knowing he had been born out of wedlock and therefore (it was assumed) "unwanted" by his mother. The adoptive mother may have been sensitive about her own inability to have a child naturally. These factors would combine to create a climate of secrecy around the adoption, even within the child's own family.

because of some way to avoid telling of genetic disposition and feeling the child may go searching and go telling others if they dont want others to know perhaps. Then tell when it is near their end as they wont be here to worry about it.

I don't know it's stupid. They should explain that it does not fking matter and let it grow up with that mind set instead of dropping a bomb shell on a fragile mind

For would feel not loved as biological parents gave them up. On top of that, any punishment even the smallest like being grounded, might be viewed by said child as if harsher punishment than it is, as they would imagine that adoptive parents don't love them.

Insecurity would be my guess. But something tells me, it's what they believe is the best for is legally their child. I know raising my own children, there were decisions I made that didn't sit well with others. My child, my choice. For the record, in the 30's and 40 and doing fine.