Lindsay Lohan's father, Michael, says he's as eager as anyone to find out if she has a half-sister she didn't know about.

As you may have heard, Michael had a romance in the mid-'90s with a Texas woman, Kristi Kaufmann, while he was separated from Lindsay's mom, Dina. Kaufmann tells OK! magazine that Michael has shirked his responsibilities to her 13-year-old daughter, Ashley.

"We were in love," she tells OK! mag. "One morning, he told me to pack my things - we were going to run off together. I waited, but he never showed up." Michael denies he left Kristi in the lurch, and says he only recently found out about Ashley. He tells us that he took a DNA test yesterday morning.

[r&m]