off topic (but still graph theoretical)

I've heard of a case where a woman married her direct uncle.¹

Now I started wondering:

Is it legally possible that she is also his direct aunt?

I don't think so, but I can't wrap my head around it ...

• "Direct" means blood related, i.e sibling of one parent, not "uncle by marriage".
• "Legal"° means without incestuous implications of the pair or their relatives (in western societies)

(FWIW marrying your cousin counts as legal, like in most western* countries, the taboo stems from medieval Catholic church law)

*) surprisingly many US states don't fall under my western definition - > Cousin marriage

°) turns out laws are so inconsistent, that I need to define it:

German rules:

• no marriage with direct descendant (Mother, Father, Grandparent, Great-Greatparent,...)
• no marriage between siblings or half-siblings ((Half-)Brother, (Half-)Sister)

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