Expression "How manyth"

Hello there,

Does it make sense if I say “how manyth” ?

For example;

how manyth son are you of your father?

how manyth president is John Kennedy?

I mean, if such a phrase is not usable, how else can I ask these questions? It sounds weird if I say “Among the sons your parents had, what number are you
chronologically?”

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Judging from the frequency with which this question is asked, it seems that every language but English has a specific structure to deal with this question form.

English does not. ‘Manyth’ is not a word. I would use something like ‘Which president was JFK? Which son are you?’, and if the response is not an ordinal number, then I would have to clarify: ‘No, I mean-- was he the 35th President? Are you the fifth son?’.

One additional comment I have is that in the English-speaking developed countries, parents have fewer children, and siblings rarely have more than a single elder or younger brother; therefore, counting children is not a common pastime.
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