How did Yoseph (Joseph) know adultery was a sin against Elohiym?

Answer From The Annual Reading Schedule - Week 10 Notes For Genesis: As in the previous question, once again, this is to point out that laws did exist prior to them being written down formally. Laws were passed down throughout the generations orally. This was easy because they lived longer back then. In fact, Adam lived until Enosh (Enos), and Enosh lived until Noach (Noah), and Noach lived until Ever (Eber) and even Terach (Terah), Avraham's (Abraham's) Father; and Noach's great, great grandson, Ever, was still alive even through the first 19 years of the life of Ya'aqov (Jacob, Yisra'el). So from Adam to Enosh to Noach to Ever to Ya'aqov, it is clear that it would not have been hard for the laws to get passed down orally even through just these 5 men.