Please stop this thread - you're making me feel OOOLD !  Most of the
books you've put down as your "first sf" weren't even written when I
started !

BUT - even with my creaky memory the first sf I read _and can name_ was
Arthur C Clarke's Sands of Mars.  Before that I read a lot of books but
never realised there was a distinction to be made where "adventure"
shaded into "sf".  In the UK there were a series of "comics without
pictures" (I'm sure there's a proper word to describe them) and they
almost all ran stories I now recognise were sf.  Dan Dare (in the Eagle)
was a much later publication.

On the cloning issue - one of the reasons I enjoy sf is the game played
between author and reader of "spot the error".  One allows for things
which are impossible (but needed to move the story on, like FTL, universal
translators etc) but try to find "internal logical errors" and it is in
this field that the latest information on cloning is useful.  SF authors
use cloned bodies to prolong life (by transferring the mind or some other
method) - then a scientist makes the comment (on the infamous sheep) that no-one knows whether she is 7 months old - or six years and seven months, because
the donor was six years old... Could be all thos stories I mention above have
the wrong end of the stick...

Now, never mind what was the first sf story you read - what's the next one
going to be ??

Keith