Finally one I can answer! That's Nan Smith's Home: Circle of Fate

Try this one:

Quote
Everybody in the family has a story on how they found out about
Dad. Mom isn't really quick to relate hers to us kids, except to say
that it was wonderful and scary at the same time. I suspect it was a
very private and emotional thing for both her and Dad, so I don't pry.
My brother told me how he found out once. He was pretty traumatized by
it - he caught Mom and Superman in bed, I guess, and put two and two
together when Mom called Superman "Clark" in a fit of passion. Let me
just be the first to say that looking in on my folks IN BED is not
something I would ever imagine my brother doing, but I give him points
for admitting to it. My sister just found out the family secret last
week, and I'm not really sure how that went down since I was here in
Gotham at the time. The list goes on.


Marcus L. Rowland
Forgotten Futures, The Scientific Romance Role Playing Game