Ferb's biological mother

Ferb's biological mother is subject in Phineas and Ferb theorizing. Phineas and Ferb only shows Ferb's step-mother, Linda Flynn-Fletcher, which raises many questions of her whereabouts.

An alien?
Some fans think that Ferb's biological mother is an alien, making Ferb a half-alien. Lala Stellune suggested that Ferb's biological mother had a child with Lawrence for world peace.

Supporting Evidence

 * Lawrence sings Alien Heart, possibly referring Ferb's biological mother.
 * Ferb's odd traits:
 * Green hair
 * Oddly shaped eyes
 * Advanced technology
 * Weird appearance in "Mommy Can You Hear Me?"
 * Speaks Martian ("Unfair Science Fair Redux (Another Story)")

Other Theories

 * A theory from TV Tropes suggests that Ferb's biological mother is French, explaining why Ferb celebrates Bastille's Day and speaks French in "Run Away Runway". Another theory suggests that she has a French-American dual citizenship.