My son is afraid of heights, and until very recently, I thought he developed this fear from a fall at some point. Granted, my husband and I couldn't think of any time when our son had a serious fall (the short fall out of his bed those few times notwithstanding).
It turns out that it's probably my fault. I have a specific fear of heights. It's weird because I'm not afraid to be on top of a mountain or a mile-high bridge and look over the edge. I'm afraid of roller coasters - but only the climb up the big hill.
It's true. I love roller coasters, but I close my eyes the entire journey up the hill. Looking over the side or over the edge makes my palms sweat. Once, my husband and I got stuck halfway up the coaster for about 15 minutes; my eyes were shut the whole time. I can't explain it - down the hill, I'm fine (maybe because we are going so fast I don't notice it.)
This recent study in Nature Neuroscience says that I may have passed that fear of heights onto my son genetically. In fairness, the scientists saw fears transferred between mice and their offspring, but I'd believe that it could be true for humans as well.
After all, it's the only theory that makes sense as to why my son clings to me when we are up high on an amusement park ride or tells me that he is afraid of heights.
Happily, he seems to have not inherited my fear of snakes, as he pet one this past weekend at our local science museum. (In fairness, I once braved a serpentarium for my son, whose main feature was a PIT OF SNAKES! I think I should get a medal for that.)
What fears do you think you've past along to your children (either wittingly or unknowingly)?