I know that a petit (trial) jury in a criminal case requires 12 jurors and I understand why the number 12 was chosen. But why does our U S Constitution, which is modeled after the Magna Carta, require 23 members of the grand jury when the Magna Carta only required 12 members of a grand jury?

Why was the number of members of the grand jury set at 23 instead of 12 by the framers of the Constitution?