At family gatherings, my sister-in-law makes critical remarks about my appearance, like my shirt's very low-cut or I might want to lose weight before wearing the dress I have on. She only does this in front of others, and she says she just tells me because she cares about me. It doesn't feel that way. I'd really like her to stop.

--Feeling Attacked

When you're female, junior high never ends. The Hello Kitty knife in your back just gets upgraded to one by Cuisinart.

Women are said to be the "gentler sex," because we rarely see one drag another out of the bar by her ponytail for a parking lot beatdown. But women aren't better people than men. Female-on-female aggression just plays out differently -- less visibly, less identifiably -- than the male-on-male kind.

Psychologist Anne Campbell explains that women evolved to avoid direct confrontation -- physical fights or calling somebody out to their face -- and instead compete with other women through sneaky "indirect aggression." This is aggression that doesn't quite read as aggression, like the public shaming that wears the plastic nose and glasses of concern.

Another popular form of woman-on-woman sneaky sabotage is spreading mean gossip to knock another woman down the social ladder and maybe even get her ostracized. There's also "constructive criticism" -- supposedly well-intentioned remarks meant to stress a woman out, make her feel bad about herself, and get her to dim her shine.

Campbell believes women's tendency to use indirect aggression is "a result of their higher parental investment" -- the fact that they're the home and ground transportation for the developing fetus and are children's primary caretakers. A physical fight (or more male-style fighting words that led to a punchout-fest) could damage a woman's reproductive parts or kill her, and an ancestral woman's survival was key to her children's survival and to her passing on her genes.

People like you, who are repeatedly victimized by another person, often don't realize they never set any boundaries, never told the abuser to stop. This effectively sends their tormentor a message: "OPEN SEASON ON ME FOREVER! Keep doin' what you're doin'!"

Whenever your sister-in-law turns a family gathering into a forum on your weight or outfit, calmly assert yourself, saying only these words: "No more comments on my appearance, please." Be prepared for her to insist you're crazy, oversensitive, and unfairly accusing her. This is bait. Do not take it. Getting into any sort of debate allows her to cast you as neurotic and mean and cast herself as the victim.

Be prepared for her to "forget" and attack you again. Simply reiterate your mantra, in a cool, calm voice: "No more comments on my appearance, please." You'll shut her up without looking like the bad guy, but you'll both know what you really mean: "Inside me, there's a skinny person longing to get out, shove a Tide Pod and load of socks in your mouth, and put your head on spin."

For pages and pages of "science-help" from me, buy my latest book, "Unf*ckology: A Field Guide to Living with Guts and Confidence." It lays out the PROCESS of transforming to live w/confidence.