An information integration theory (IIT) study aimed to explore Mexican youngers’ systematic thinking underlying judgment and attitudes toward heterosexuals, gays and lesbian’s rights for adoption. Here, 126 heterosexuals were required to take a cognitive algebra study consisting of 36 experimental manipulated social scenarios, each describing different couple adoption situations. The participant’s experimental task was to provide an acceptability judgment by using a scale. Results showed, acceptability judgment varying from moderately favorable to not favorable that was regulated by two different cognitive rules. A cluster of participants having the higher index of acceptability showed systematic thinking moderated for a summative cognitive rule whereas judgment from another group of participants with a lower index of acceptability was moderated by a multiplicative cognitive rule. In both cases, the most relevant factor to consider was the couple romantic relationship stability. Theoretical and methodological implications are discussed in this article.