According to studies examining adopted children, their criminality tends to resemble more that of their __________.

The correct answer emphasizes the influence of genetic factors on criminal behavior. Research into adopted children has shown that their propensity for criminality aligns more closely with that of their biological parents rather than their adoptive parents. This suggests that genetics play a significant role in influencing tendencies toward criminal behavior, highlighting the heritable aspects of such traits.

Adoptive parents contribute environmentally, but their influence does not outweigh the biological factors that are inherited from the child's genetic origin. This finding underscores the nature versus nurture debate in criminology, where biological factors may set the stage for potential criminal behavior, while environmental factors, such as those from adoptive parents, may less significantly impact an individual’s propensity for crime.

In contrast, guardians and friends typically reflect social and contextual influences rather than genetic predispositions, which do not account for the stronger connection observed with biological heritage. Therefore, the research indicates that inherited traits can significantly influence behavioral patterns, including criminality, in adopted individuals.