Are humans designed to be symmetrical?

We all have two of a lot of body parts. But it seems like while we things are generally symmetrical, there are lots of flaws and imperfections.

- Eyes. I have known several people with a left eye of one color and a right eye of another color

- Arms (and to a lesser extent legs) where one arm is ¾ to an inch shorter than the other

- Feet: most people have feet of slightly different sizes; no more than a ¼ inch (or one size) different, but they’re not the same

- Breasts. Possibly most visible. Different sizes, different placement on the chest, one points more out, the other more straight ahead.

- Ears. Some people have one a little higher or lower, or front or back, than the other

There are probably more examples, but these are what come to mind.

And I am not even talking about internal organs, such as lungs and kidneys.

Why would evolution, otherwise so effective, have resulted in these odd asymmetricities?