Twins (1.3, 3.1) A researcher studied a group of identical twins who had been separated and adopted at birth. In each case, one twin (Twin A) was adopted by a low-income family and the other (Twin B) by a high-income family. Both twins were given an IQ test as adults. Here are their scores:48 Twin A: 120 99 99 94 111 97 99 94 104 114 113 100 Twin B: 128 104 108 100 116 105 100 100 103 124 114 112

(a) How well does one twin’s IQ predict the other’s?

Give appropriate evidence to support your answer.

(b) Do identical twins living in low-income homes tend to have lower IQs later in life than their twins who live in high-income homes? Give appropriate evidence to support your answer.