Marshall, the 23-year-old starter for the Chicago Cubs, and his twin brother, Brian, have had a baseball in their hands -- their left hands to be exact -- since a very early age.
"I guess [my dad] kind of molded us into left-handed pitchers when we were real young," Marshall said. "I think my twin brother, he was actually right-handed. But when I started throwing left-handed, he figured we were both left-handed, so he forced the ball in my brother's left hand too."
From nearly making the Little League World Series to nearly making the American Legion World Series, Nelson Marshall was always right there, coaching his twins.
Then in June 2003, when it was time for the Major League amateur draft, Nelson Marshall saw his "plan" had worked to perfection.
After receiving a call that Brian had been selected by the Boston Red Sox with the 144th pick, the Marshalls didn't have to wait long before they learned the Cubs had taken Sean with the 163rd pick.
"We got drafted within like 15 minutes of each other," Sean Marshall said. "[Brian] was taken in the fifth round and I was taken in the sixth round. [My dad] was a very proud guy that day."
Sean would continue to make his father proud of his baseball career, making his first career start on April 9 against St. Louis.
"You could tell [my dad] and my grandparents and everybody, they were all very proud and very excited to be here for that St. Louis game," Sean Marshall said. "It was bringing tears to their eyes -- that was pretty cool."
Ryan Crawford is an associate reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.