This is my Christopher theory... and I'm really on the edge of speculation so I don't have a probability assessment to go along with it
It could be possible that Christopher was a child of Jonathan and Martha's that didn't survive. This could have put a strain on the relationship which led to Martha and Clark needing to stay with the grandparents for a while. Where in that timeline Clark would have entered--there are many possibilities, so I'll quit while I'm ahead/behind/neutral/wherever.
Oh, and BTW: I hate Lana on principle too. My eyes unconsciously narrow every time her name pops up.
~Sonia
/eyes Carol's ACME bomb warily and wonders how to hitch a ride on HG Wells' time machine
