Since Jesus did not specifically address homosexuality, how can we be certain he considers it sinful behavior?

Question: Since Jesus did not specifically address homosexuality, how can we be certain he considers it sinful behavior?

Jesus addressed a multitude of sins throughout the four Gospels. As evidenced in the Sermon on the Mount, he explicitly affirmed the continuation of the Old Testament moral law and its intensification in his kingdom. 

At the same time, there are many specific issues, both ancient and modern, for which there is no specific scriptural text explicitly revealing what Christ said during his earthly ministry. This does not mean we cannot know what Christ believed and taught. 

In answering a question about divorce, Jesus himself stated that God's plan from the beginning was that a man and a woman be united in marriage. Jesus affirmed the Genesis pattern of complementarity, and he honored the institution of marriage as the conjugal union of a man and a woman (Mark 10:2-9). 

At every single point, Jesus affirmed the Old Testament's judgment against sexual sin. Moreover, he pushed the point even deeper by moving from the Old Testament's prohibition of the external act to an even bigger concern-the sinful nature of the human heart.