"The place I was born" vs. "The place I was born in"
Solution 1:
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This is the place where I was born. No need for in, for geography.
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Let's say you were born in an ugly hospital building and you want to stress that:
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This is place I was born in. [to be born inside a location]
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This is the family I was born into. [to be born into a family]
Unlike: I don't know where they are at.
The "at" is always non-standard.