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Families are different from one another and so family trees as well.
Have a look at The Simpsons Family Tree.
Homer is Lisa's father --------------------------- Lisa is Homer's daughter.
Marge is Bart's mother -------------------------- Bart is Marge's son.
Maggie is Bart's sister --------------------------- Bart is Maggie's brother.
Homer is Marge's husband----------------------- Marge is Homer's wife.
Herb is Lisa's uncle ------------------------------ Lisa is Herb's niece.
Selma is Bart's aunt ----------------------------- Bart is Selma's nephew.
Abraham is Maggie's grandfather ---------------- Maggie is Abraham's granddaughter
Abraham and Mona are Bart's grandparents ----- They are Abraham and Mona's grandchildren
Who are the rest?