If you look at the etymology of names, you can see how certain names have come to be, but to an outsider unfamiliar to the language, what makes an English name sound masculine or feminine?
I've been specifically thinking about rhyming names.
Girls: Doris, Chloris, Loris (in use in the USA in the early 20th century)
Boys: Norris, Boris, Morris, Horace
Why aren't Toris or Voris names? Thoris sounds kind of cool; someone should use it if they haven't already.
Girls: Carrie (although Cary and Carey sometimes are used for boys), Mary, Sherry, Fairy (used in late 19th-early 20th century)
Boys: Barry, Gary, Harry, Jerry, Larry
Perry and Terry can go either way. I've seen Derry/Dary as a short form of both Deirdre and Daryl/Darren.
Why aren't Narry or Sarry names? Would they be masculine or feminine? English doesn't seem to have any strict conventions about endings on names that point specifically to genders. Sure, most names ending in -a are feminine, but then you have all the Biblical names like Jonah, Noah, and Joshua, which sound perfectly fine for boys.
Darragh is a boys' name in Ireland. Dara is mostly feminine in the USA, as are Sarah, Cara, Mara, Lara, Farrah, Tara, and Zara. Now, you can pinpoint all the origins of these names, most of them come from different places (i.e., Sarah is biblical, Lara is a Russian short form of the Greek Larisa), but they are all commonly used in English. Americans have cherry-picked the names from other cultures/Languages that they liked to use and the -ara sound sounds good to our ears. We have even coined new names based on this sound, resulting in Shara and Jerra. Why not Para or Vara?
These are the things I think about when I can't sleep.