Why in English both Dad's brother and Mom's brother called uncle
and the same with cousin , aunt , etc.
And How can we distinguish between them?
These family distinctions are not particularly important in British or American culture. That's why we have no special words for them in everyday language.
For the same reason we do not have a natural question in English to ask "Paul is your how manieth brother?". We don't have the question because we don't feel the need to ask it.
Context is important. Please provide enough for us to be able to deal effectively with your question.
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