Though many believe the names to be "the same just male and female versions".. Aaron and Erin are NOT the same, or even similar names. Only in sounding are they related. Aaron is a biblical name with Jewish origins, while Erin is Gaelic Irish. Aaron is almost strictly masculine, while Erin is unisex though much heavily popular as a feminine name.
In 2018, 21 is the most common age for an American (U.S.) Aaron who is a registered male with the Social Security Administration. It is the 95th most common male first name for living U.S. citizens.
For those of you who don't like the spelling of this name, you have two options. You can drop one A, or you can add the H, for Aharon, which is the original and more accurate transliteration of the name. It really is that simple.