What is odd about William Shakespeare birthday?

Answer 1

We do not have a record of his birth. We know when he was christened, and children in that time were usually christened three days after their birth, but there is no documentation to confirm it.

Answer 2

It is also his death date. However, there is no solid evidence for April 23 being his birthday unless the label on the Sanders portrait is genuine, which means that April 23 was chosen as his birthday because a) it is a few days before the day of his baptism, April 26, b) it is St. George's day, and c) he died on April 23. When you know that the reason April 23 has been chosen as his birthday is that it happens also to be the day he died on, it becomes a lot less odd. It's like saying "Here's an odd coincidence: the New York Yankees play in a stadium called Yankee stadium. What are the chances of that?"