Micheal B. Lewis suggests the reason multiracial people are perceived as more attractive is that genetic diversity makes people more attractive by virtue of their apparent greater "genetic fitness." In other words, others take the ethnically ambiguous faces as indicators of greater genetic diversity which is a cue for apparent healthiness. This is known as heterosis. A 2005 study conducted by Craig et al. (as cited in Latson) lends support to heterosis. The study focused on people who had inherited a different gene variant from each parent in a section of DNA playing a vital role in the regulation of the immune system. Heterozygous men –with two different versions of these genes –were more attractive to women than homozygous men (men with the same version of these genes). Although this study was not conducted on multiracial people, specifically, having parents of different races makes you more likely to be heterozygous.