Finally I remembered it! It's wonderful Twins by Nan Smith! Another great story of hers!

I'm going to search another one...

A revelation scene:

Quote
"Smallville, Kansas, May 17, 1966," said Clark quietly.

"Pardon?" Lois didn't even bother looking up at the apparent non sequitur.

"I told you that, if you found the records, and if it became necessary for you to know where and when the ship landed, I would tell you."

That got her attention. Her head jerked up, and she stared at him, wide-eyed. "*What* did you say?"

"I said-"

"No. No, it's all right. I heard you the first time. I'm just... *You're* Superman? You?!"
simona smile