Ethan is Jacob's brother and Sophia's brother as well. Since Sophia is Lucas's mother, her brother, Ethan, would be Lucas's uncle. Therefore, Ethan is Lucas's uncle.

Sarah is Jacob's spouse. Sophia is Jacob's sister and thus Sarah's sister-in-law. So, Sarah would be Sophia's sister-in-law.
Jacob has two siblings, a brother named Ethan and a sister named Sophia. Sophia married Michael, and they have a son named Lucas. Jacob is married to Sarah, and Ethan is single. How is Ethan related to Lucas and what would Sarah be to Sophia? Make your response very short.