Luke Grimes

Last spring, the Walker clan learned that a boy named Ryan, and not Rebecca, was their long-lost illegitimate kin. Since then, Kevin and Sarah have been on the hunt to locate said sib.

Well the search is over, casting-wise at least, and the winner of the Ryan Walker Derby appears to be... Luke Grimes.

Not Gregory Smith or Scott Porter or Jason Ritter or Jason Dohring, but Luke Grimes.

This news, which is just a signed contract away from being official, was first reported by EW's Ausiello.

Grimes' few credits include the nearly (save for Amber Heard) unwatchable horror pic All the Boys Love Mandy Lane, which as far as I know was never released.  (And no, Mickey, he isn't related to ER's Scott Grimes.)

Look for Ryan to surface (and in short order be befriended by Rebecca) around midseason.