Human geneticists have turned to studies of twins .
人类遗传学家一直把注意力转向对双胞胎的研究。
Dna holds our genetic code , and geneticists have studied it for decades .
dna携带了我们的基因，基因学家已经研究dna几十年了。
In addition , within the last three years molecular geneticists have begun to extract dna from ancient human skeletons and compare the genes of japan 's ancient and modern populations .
