This experimental study examined the effects of biological attributions on individuals’ beliefs and attitudes toward transgender people and the moderating role of right-wing authoritarianism (RWA). We randomly assigned 183 Chinese university students (men: n = 85, women: n = 98) to read one of three fictitious articles. The first article suggested that transgender identity was causally linked to biology (biological determinist condition), the second one highlighted the interplay between biological and environmental factors (epigenetic condition), whereas the third article did not mention the origins of transgender identity (control condition). Consistent with the biased assimilation hypothesis, the effects of biological attributions depended on individual differences in RWA. Low-RWA participants showed higher levels of naturalness and discreteness/homogeneity beliefs about transgender identity in the biological determinist condition than those in the control condition. By contrast, high-RWA participants displayed higher levels of discreteness/homogeneity beliefs but similar levels of naturalness beliefs when they read the biological determinist message compared with the control group. Low-RWA participants showed higher levels of naturalness but similar levels of discreteness/homogeneity beliefs in the epigenetic condition compared with the control, whereas high-RWA participants exhibited lower levels of naturalness and higher levels of discreteness/homogeneity beliefs when they read the epigenetic message compared with the control group. This study also suggests that, contrary to attribution theory, presenting information regarding the biological basis of transgender identity does not necessarily lead to more positive attitudes because (a) it triggers essentialist thinking and (b) the effects of biological attributions depend on recipients’ authoritarian dispositions.