Gretel Doofenshmirtz

Grettle Doofenshmirtz was Heinz's Doofenshmirtz's Great-Grandmother who was a great cook, specifically in creating a meatloaf recessipy with the secret ingrediennt of "Hate". She passed it onto her son: Hozé Doofenshmirtz (wierd Story) who passed it on to Heinz Doofenshmirtz's Unnamed Mother who passed it onto Roger. Heinz than stole it. ("Meatloaf Surprise") According to Heinz Doofenshmirtz Great-Gradma Grettle had "Issues". Hozé Doofenshmirtz might not have been her son but some sort of close realitive like a nephew do to hozé likely being from Mexico or Spain.Heinz might've known his great-grandmother personally sense he said that she had "Issues" as if he knew what they were. Of course it is possible that he was told this by his grandpa Hozé or his parents.