"Bewegen Sie nicht!"
"Are you a man or a schnitzel!?"
Past and Present Life
He owned a Spiztenhound puppy which, according to him, was like the son he never had and named him Only Son. He won Only Son in the game "Poke the Goozim With a Stick", which then grew up to become an award winning show dog, bringing him fame and fortune. ("Lawn Gnome Beach Party of Terror", "Got Game?")
He shows favoritism toward his younger son Roger, when his older son, Heinz was made the lawn gnome, and not Roger. ("Lawn Gnome Beach Party of Terror")
He never payed attention to Heinz, so he often felt left out and worthless.
On Father's Day, Heinz decided to go back to Drusselstein to retrieve his father's repossessed lawn gnome and hopefully try to make amends. However, when Heinz comes in with the lawn gnome, he trips on the rug and the gnome smashes to pieces. His father tells him that Roger gave him a bigger lawn gnome that is more impressive because it makes espresso. But his father decides it is the thought that counts. Heinz leaves disappointed, but after he leaves, his father sees the gnome with the serial number of the gnome that was repossessed so many years ago. Later, he is seen glueing the shattered gnome back together and telling the gnome not to move, just like he told Heinz to do in his youth.
Unlike his own children, Mr. Doofenshmirtz generally loved and cared for the family's pet dog Only Son who brought the family much fame and fortune.
Roger is the second son of Mr. Doofenshmirtz, though they have not interacted or even been seen in the same scene together since their respective debuts. None-the-less, Roger seems to have a much better relationship with his father than his brother's relationship to him, though this is not saying much. It appears that they are on fairly good terms at least in the present, as Roger sent him a Gnome-shaped espresso machine that was taller than him.
Mr. Doofenshmirtz is one of the main driving forces behind Heinz's rather "evil" way of life. He "refused to show up" for Heinz's birth or attend any of his self-thrown birthday parties, denied him the basic rights of childhood, and even briefly disowned him. However Heinz appears to generally wish to reconcile with his father and even considered using an inator to make him love him. ("Fun House") When he greeted his adult son for the first time on screen he showed apathy towards his son's "gift of rubble", however when Heinz left Mr. Doofenshmirtz noticed that the rubble contained the serial number DAEHM23 and deduced that the gift was actually his beloved Lawn Gnome. He has repaired the gnome but their relationship is still strained at best.
- Most of the words he says are in German. They are: "Bewege dich nicht!" ("Do not move!") in Lawn Gnome Beach Party of Terror (flashback), "Nеіn!" ("No!") in Not Phineas and Ferb, "Zu nah!" ("Too close!") and "Ich habe keinen Sohn." ("I don't have a son." or "I have no son.") in "Split Personality". The only words he has been heard speaking in English before "Father's Day" were "Are you a man or a schnitzel?!" in "Split Personality."
- In "This Is Your Backstory", it appears that he looks the exact same since Heinz's childhood meaning that he looks the same now as he did than for no-less than 47 years. But in "Father's Day" he is seen as an old man.
- The only childhood backstory of Heinz that his father has not made so much as a cameo in is the backstory when Heinz explains his past birthday troubles, where his father is absent from both his birth and later birthday parties.
- "Lawn Gnome Beach Party of Terror" (First appearance) (Appears in flashback(s))
- "Lawn Gnome Beach Party of Error!" (Spot the Diff episode) (Appears in flashback(s))
- "Got Game?" (Appears in flashback(s))
- "At the Car Wash" (Appears in flashback(s))
- "Phineas and Ferb Christmas Vacation!" (Pictured only)
- "Not Phineas and Ferb" (Appears in flashback(s))
- "Split Personality" (Appears in flashback(s))
- "Rollercoaster: The Musical!" (Appears in flashback(s)) (Cameo)
- "This Is Your Backstory"
- "Father's Day"