We focus on liquid crystals (LCs) doped with deoxyribonucleic acid (DNA). We have researched the effect of the single strand DNA doping on the LC molecular alignment structure in terms of the kind of base (adenine, thymine, guanine, and cytosine), the concentration, and the molecular weight of DNA. As a result, it is found that the DNA doping can induce a twist deformation of LC alignment. Furthermore, the twisted structure strongly depends on the kind of DNA base.