Use of "one of" with "and" and "or."

"Are you related to George and/or Mike?"

Some people don't like the "and/or" construction, and some people really don't like it when it's spoken rather than written. Unless you need to be especially formal, though, I would say that the advantage of eliminating the need to clarify the question further is likely to outweigh the awkwardness of it.

The answer is certainly "and", but it is not always obvious. In the specific question you might be related to both George and Mike, which I think makes it a confusing example.

Suppose we rephrase the question to be an exclusive 1-of-n choice, and compare the two phrases:

• Choose red, blue, green or yellow.
• Choose one of red, blue, green and yellow.

The phrases seem almost the same and it's easy to see why you might use "or" in the second phrase. In spoken language I don't think anyone would notice.

Logically, you can think of the second phrase as meaning:

• Choose one from this list.
• The list is red, blue, green and yellow.

It would not be logical to use "or" in defining the list, so it just as illogical to use it in the phrase with "Choose one of".

That being said, language does not always follow logic.