(In the MCU) Steve Rogers was born July 4, 1918 to his parents Sarah and Joseph Rogers in Brooklyn, New York. (Technically just Sarah because in May 9, 1918, Steve’s father, Joseph, died in World War I due to mustard gas.)
In 1930, age 12, Steve meets his best friend Bucky Barnes.
Steve attended George Washington High School in Brooklyn, New York City from 1932 to 1936.
He also attended Auburndale Art School, also in Brooklyn, from 1937 to 1938 until he was about 20.
On June 5, 1940, his mother, Sarah, died of tuberculosis when Steve was 22.
In 1941, he began enlisting for the war.
In 1943 he and Bucky went to the the New Work World’s fair and Steve was finally allowed to enlist in the war as a candidate for Project Rebirth. I assume he was given the serum in either late 1943 or early 1944, age 25.
In 1944 Bucky fell from the train and was assume dead.
Stebe crashed into the ice and froze in 1945 when he was 27.
He was found and unthawed in 2011 when he was 92, biologically still 27.
The events of the Avengers took place is 2012.
The events of Captain America: The Winter Soldier took place in 2014
The events of Avengers: Age of Ultron took place in 2015.
Today, July 4th, 2015, is his 97th birthday, but he is biologically only about 31, which is 3 years younger than Chris Evans.