Rashi on Genesis 36:15 and biology

2 Shvat 5770


Genesis, chapter 36, verse 15 says “These are Leah’s sons that she delivered to Jacob in Padan Aram and Dina his daughter…”.

Rashi explains: “The males he referred to Leah and the females to Jacob, to teach you that whenever a woman seeds first, she will deliver a male, and whenever a man seeds first the woman will deliver a female."

How Rashi’s commentary is explained biologically?

Is there any connection to the ovum and the sperm reaching each other to generate fertilization?


The Y chromosome lives less time than the X chromosome. So, if Y was produced earlier than X, there is more probability of getting the XX combination (female) than the XY combination (male).