The hospital makes a colossal blunder and informs you your baby is not your biological child.
-At 1 week old I would certainly want to exchange it for my biological child.
-At 16 years old, biology or no, that child has become mine in every way that matters and I would not want to exchange him/her for a stranger.
Of course every parent would want to get to know their biological child, but what age would you consider replacement unacceptable?
Honestly, fifteen minutes after my baby was put in my arms it would have been traumatic. I would certainly want my biological child as well, but I wouldn’t have been willing to give him up.
Wouldn’t have been possible. I knew what they looked like starting from about 1 minute after each one emerged from my body.
This question reminds me when one of my aunts swapped her kid with the lady next to her in the hospital for a preferred gender and then took her bio kid back a few weeks later.
The story is an excellent example of why my nuclear fam and I stay away from 95% of our biological/extended relations.
One of my mom’s brothers is slightly slow & mentally ill but because of arranged marriage being what it is, the family managed to get him married off. The reason is most likely because he was, at one time before all the anti-psychotics made him severely overweight, extremely good looking. Like Clive Owen-ishly hot but with chestnut brown hair, white skin & green eyes, which is a type of coloring/look that seems to function like catnip to Indians for some reason.
Anyway, his wife pretty much loathes him because he is slow and insane and the hot wore off as they had to up the dosage on his drugs.
However, they have 3 kids together. The first two were boys and apparently my aunt was dying for the 3rd to be a girl (which is the only reason she tried for the third time) but she got another son. The lady next to her in the hospital had 4 daughters and was on a last try for a son but had just delivered her 5th daughter.
So they swapped. My aunt kept the girl for a couple of weeks but apparently felt a combo of guilty + worried about the fact that the baby wasn’t light-eyed, as everyone on that side of the family has blue, green or tea colored eyes.
So they swapped back after my aunt brought the baby to the lady’s village and made a fuss about it.
The best part was that she got drunk and told my sister this story (at least she had enough good sense not to tell my cousin, who has grown up in blissful ignorance and is actually a really sweet, successful human being) about 10 years ago and actually had the gall to same something like “yeah, and then when I took him back and heard him crying…I knew, that was MY KID and I couldn’t swap him, even though I really wanted a girl,” lauding her motherly instinct and all of that.
My sister actually blabbed the story to my me and my parents, though we’ve never told anyone in our family because my cousin doesn’t deserve the stress over something that happened a couple of decades ago. Because the four of us are judgmental and closed-minded and totally not cool with casual baby-swapping, we were fairly horrified, though.
I don’t know, I’ve been thinking it would be okay to start the switch at about 12.5 yrs and switch back after 22 or so. I am on my third teenager. I think if I swaddled him up in a blanket and snuck him into the hospital, no one would be the wiser.
Oh, so very true! But the OP was about *swapping *-- that would mean you’d have to take on somebody else’s teenager.
Oddly, I usually can muster up my patience for other people’s teenagers more than for my own. 
My poor kids…
Never. They can keep the other kid. This one is mine.
When my son was somewhere around 4-6 months old, I remember thinking that if I got a call from the hospital telling me there had been a mixup and to come get my real son, I would have told them to fuck off – I have my real son, as far as I’m concerned. The cut-off may have been even younger than that, I don’t really know… but I do know that after that cut-off, I wouldn’t give a damn about getting to know my biological kid, ever, period. In a similar vein, if I learned today I was adopted, I couldn’t care less about who my biological parents were - they never (hypothetically) factored into the equation before, and they never would.
There was a This American Life episode about two girls who were switched at birth. One of the mothers figured out what had happened fairly early on, but kept quiet about it…for more than 40 years. It was a very strange story. Here’s the link, you can stream it online for free: http://www.thisamericanlife.org/radio-archives/episode/360/switched-at-birth