The American Dad! episode you're looking for is (Season 3, Episode 4), which originally aired on November 4, 2007. Plot Summary
: This episode reveals that Francine’s smarts are the reason her adoptive parents left her out of their will; they believed her sister Gwen was a "moron" who needed the money more. You have requested : American.Dad.S03E04.MP4.LE...
: When Francine’s Chinese adoptive parents, Ma Ma and Ba Ba , visit unannounced, Stan becomes frustrated by their refusal to follow his "man of the house" rules. To replace them, he tracks down Francine’s biological parents, Nicholas and Cassandra Dawson, only to discover they abandoned her as an infant just to get a first-class flight upgrade . The American Dad