How many different possible distinct combinations of DNA are there? I.e. what are the odds that somebody else (not a clone) would have the same DNA as me.
It’s bernard, just under new management
There are a huge number of possible DNA combinations but the vast majority of which don’t encode squat. Plus, DNA comes in different lengths depending on the organism. But I’m assuming you’re talking humans here.
Roughly speaking, the human genome has three billion base pairs (IIRC) and each base pair can be one of four nucleotides so that’s 8x10^37 possible combinations of nucleotides. But an extremely small percentage of those would actually “encode” a human. Or anything at all.
Still, allowing for genes that must remain mostly intact in order for you to still be a human, there’s still a whole heck of lot of room for mutations, insertions, deletions.
I’d say if you run into someone with identical DNA, your an identical twin or you’ve been cloned. Or you are a clone.
Now the odds of someone having an identical DNA “fingerprint” as you is more common. But still remote.
Wow! Thanks for the info. Out of curiousity, what would those that wouldn’t encode a human encode? A pile of goo? Someother biped? Something else entirely? Do we know?
Thanks again (so much for trying to beat that murder rap by saying it was a DNA equivalent in China).
It’s bernard, just under new management
Think of it this way. What are the odds that given a blank piece of paper a pen and a ruler, I could recreate a blueprint of your house by drawing randomly placed lines? Chances are I wouldn’t even get anything even resembling a blueprint, let alone a blueprint identical to your house.
I’d occasionally get four lines that enclose a space, but it wouldn’t really be practically considered a room. Similarly, DNA can encode a random protein by any sequence that has a “start” a “stop” and anything in between. That doesn’t make it a biologically functional protein. So most of these random DNA combinations would just be a series of nucleotide groups that encode useless polypetides interspersed with even more useless sequences.
There are regulatory elements and what-not that do not encode proteins, but that’s getting in too deep.
Glad I could help 
Sometimes I wonder what encodes for posting to SD forums. 
It’s sure to deselect sometime soon.
Ray
“junk” DNA is actually the REM statements in our genetic code.