Final answer:
During early adolescence, typically in middle school, cliques become more heterosexual and include both sexes as children broaden their social interactions and form mixed-gender groups.
Step-by-step explanation:
Cliques become more heterosexual and include members from both sexes usually during early adolescence, which is around the middle school years. This is the stage where children broaden their social circles and begin to form mixed-gender groups, often influenced by the onset of puberty and the awakening of romantic and emotional interests. At this time, they might join various social activities that encourage heterogeneous mixture, such as sports teams or scouts, providing opportunities for interaction between the sexes beyond earlier same-gender play groups.