Mary-Kate Olsen is just one half of the Olsen-twin duo, and she is the twin who allegedly struggled the most with drug and substance abuse. In 2004, she checked into rehab for anorexia and an alleged drug addiction.

Which Olsen twin has a disease?

Ashley Olsen has been diagnosed with Lyme disease.

Why does Mary-Kate and Ashley Olsen look sick?

Onlookers were quick to notice her pale skin and frail appearance. According to the source, the former child star has been suffering in silence with Lyme disease, after she was bit by a parasite several years ago. Shes really sick.

How rich are the Olsen sisters?

With their acting, business and fashion earnings combined, Mary-Kate and Ashley have an estimated net worth about US$250 million each.