In studying bereishis I have come up with questions about Joseph and his brothers that have long bothered me. One question is in parsha vayeshev, where we read how Joseph was sold by his brothers to the "Ishmaelites". I have always taken that to be the descendants of Ishmael. Isaac and Ishmael were half brothers. Which means that Isaac’s sons, Jacob and Esau were first cousins to Ishmael’s sons, which in turn means that Jacobs twelve sons were second cousins to Ishmael’s grandchildren. Didn’t the Ishmaelites know they were buying their second cousin? I would certainly know if my second cousins tried to sell me another second cousin as a slave! What have the rabbis said about this?
An idea that was sparked by a similar line of reasoning in this post from the Parsha Blog:
Yosef was sold 182 years after Yishmael was born. (That's 14 until Yitzchak is born, 60 more until Yaakov is born, and Yaakov is 130 when he stands before Par'oh after 22 years of Yosef being away = 182 years.) Just because Yitzchak and Yaakov waited a long time to have kids doesn't mean Yishmael or his decendants did. If Yishmael and all his descendants each had 5 kids by the age of 30, that means Yishmael had at least 5^6 = 15625 great-great-great-great-grandchildren running around at the time Yosef was sold. So it shouldn't be too surprising that they didn't know (or care much about) their long-lost 2nd half-cousin thrice removed.