Tested so similarly over time. not just in these exams, but the s.a.t. i understand and standardized testing. the research, dr. siegle, it would surprise you if they did not have similar results. tell us why. >> that's correct. a vast number of psychological studies as well as life histories do show that identical twins perform at an amazingly similar level. even identical twins raised apart from birth. and how do we explain this? identical twins have similar dna. they come into the world with the exact set of genes. and we know from our research studies that genes predispose us towards certai...