It seems Lindsay Lohan got an unwelcome surprise over the weekend: an announcement of a new baby sister.Except the announcement wasn’t for a baby, but a 13 year old sibling none of the Lohan’s knew existed until last week.

More pics after the skip…

The Lohan dad – Michael – seems to have had an affair with a woman during his brief separation from mom Dina back in 1995.  The result – a love child who is now 13 years old!  Just what the Lohan’s needed to enjoy a calm summer for once…a sibling scandal!