Why Wasn't I Told This?

So I was on one of my Wikipedia whims the other day and ended up checking out the history of the comic strip "Beetle Bailey"



It was then that I noticed a link to the comic strip "Hi and Lois"



Now.....I have been reading both these comic strips for years...so how is it I was completely unaware of the fact that Beetle Bailey and Lois Flagston are brother and sister? I've racked my brain, but can remember no mention of the fact in either strip. I only get "Hi and Lois" as a Sunday strip, so is it possible it's been mentioned during the dailies? The two characters don't even look alike, and besides, even though they're two different strips, you'd think there would be some mention of that fact periodically. I can't stand it when I'm involved with something for years then discover some basic fact about it. Why wasn't I told this?