If Karina is currently 40, and she is twice as old as her brother, then her brother is currently 40/2 = <<40/2=20>>20 years old.

If Karina was born in 1970, then her brother was born in 1970+20 = <<1970+20=1990>>1990

# Answer

1990
<|im_start|>system
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<|im_start|>user
Karina was born in 1970 and she is currently twice as old as her brother. If her current age is 40, in what year was her brother born?
Please reason step by step, and put your final answer within \boxed{{}}.<|im_end|>
<|im_start|>assistant

user
1990
Karina was born in 1970 and she is currently twice as old as her brother. If her current age is 40, in what year was her brother born?
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