Yes. It is really normal, like sweetyalissa said, that breasts are different. Where did you even find information about cancer and pregnancy online?!?! That is just crazy talk! This, and it shocked me, has been brought up on the forum before. Really! I mean, we learned in school that as far as hands, feet, even how fast the hair grows, can be different on the right side and left side of the body. When I was a child I learned that I must always try my shoes on my right foot (when shopping) or else they might be too small when I get them home. And rings definitely don't fit both hands the same way. Sit firmly and evenly with your back to a straight wall. You might notice that when you line your feet up, one leg is longer. What are people learning in school, these days!? 
