lead to the prediction that being reared by the same parents would make children more alike, or that being treated differently by parents will make children different from each other. Behavioral ...

Same signs give a positive: \(3 + (+2) = 3 + 2 = 5\) Same signs give a positive: \(3 - (-2) = 3 + 2 = 5\) Different signs give a negative: \(3 + (-2) = 3 - 2 = 1 ...