Old enough to play TV moms?

The new CW series Life Unexpected follows in the TV tradition of casting unrealistic mom/child pairings. We do the math, using the actors’ real ages at the time.

Life Unexpected (2010)
Shiri Appleby (Cate), 31
Britt Robertson (Lux), 19
Mom would be 12 at birth

Terminator: The Sarah Connor Chronicles (2008)
Lena Headey (Sarah), 34
Thomas Dekker (John), 20
Mom would be 14 at birth

Kath and Kim (2008)
Molly Shannon (Kath), 43
Selma Blair (Kim), 36
Mom would be 7 (!) at birth

Gilmore Girls (2000)
Lauren Graham (Lorelai) 33
Alexis Bledel (Rory) 19
Mom would be 14 at birth