Wikipedia tells me that stretch marks are a form of scarring on the skin caused by tearing of the dermis (that being the layer of skin beneath the epidermis). They can appear anywhere on the body, but particularly in areas where large amounts of fat are stored: abdomen, breasts, upper arms, under arms, thighs, hips, butt. There's no mention on Wiki of stretch marks being undesirable, only about the fact that they don't pose any safety risk, which is awesome. But throw the phrase in a quick Google search and you'll see that a huge percentage of the results are about removing them.
Pardon my LOLCat speak for a moment...
Stretch marks: I haz them.
Two rounds of 'em, as a matter of fact. When I was 11 or 12 I basically sprinted through puberty - I think in one year I gained fifty pounds and grew eight inches. I remember being most self-conscious about the stretch marks on my hips, the ones you could see when I lifted my arms up enough that my shirt rose up on the sides. Eventually I started noticing that almost everyone has these kinds of stretch marks - seriously. Pretty much every woman I know has stretch marks somewhere on her hips, butt, or thighs. Most of the time they're small and not noticeable, but seriously. Tons of guys, too - just pay attention to the shoulder-underarm area of the weightlifters next time you're at the gym. Pretty much everyone has them.
But then I gained some weight and gained some new stretch marks. At first I freaked out about it, bought and applied one of those stupid creams, and probably did some crying. I got some stretch marks on my upper arms - very difficult to hide, and some on my tummy - shameful because I thought only pregnant moms got those, and some on my breasts - previously mark-free and a source of much vanity on my part.
Basically, it just made me even more ashamed and embarrassed about gaining weight. At least that's temporary. I figured I was stuck with visual evidence of my own laziness and poor self-worth for all time.
But gradually, over the past year, most of those stretch marks have faded to practically invisible or not noticeable enough to be worried about. I've done a little research and there's no great way to get rid of them - surgery for stretch mark removal isn't really a guaranteed option these days. Not that I would go for that, but it would've been nice to know, I guess. I've more or less made peace with my body, something that's much, much easier to do now that I'm seeing some results of my hard work.
(Related sidenote: The scale this morning said 184, twenty pounds less than my highest weight ever in January. Heck yeeeesssssss!)
So I'm writing about stretch marks because it's just one of the things on the long list of potential areas of self-hatred of our bodies. And, especially since this one is something nearly everyone has, WHY?! I know better than to think that our insecurities can be completely overcome by logical reasoning (for example, "everyone has ___; this imperfection doesn't make me gross or unlovable or unattractive") and I wish I knew the right solution. I think it's different for everyone.