Lindsay Lohan Slams 'Sick' Rumors About Her Sis

Lindsay Lohan may be used to tabloid gossip about her own life. But she's fighting mad over recent rumors swirling around her 14-year-old sister Ali.

The 22-year-old actress took to her blog Thursday to slam online speculation that her little sis may have undergone breast augmentation. In fact, Lindsay said she was confronted by a photographer who yelled, "What do you have to say about people commenting on your sister's implants?"

"It made me feel a bit sick to my stomach," Lindsay wrote on her MySpace Celebrity Blog.

The actress – who's preparing for her recurring role on Ugly Betty – said she's "not judging" people who do have cosmetic surgery.

"But all in all my mother taught us to appreciate what we have been given," she wrote. "Nor would she ever encourage, or allow a 14-year-old child to alter her body."

Ali's rep also confirms to PEOPLE that the 14-year-old has not has breast augmentation surgery.

Lindsay's blog entry also gave some insight into her mood. Although she just scored some "great clothes" from Alexander Wang, she admitted: "I miss Samantha [Ronson] cuz she's out of town :("