My uncle Larkin was named after his father, who was named after his grandfather, Larkin Barnett. The name apparently comes from the Irish, meaning 'rough, fierce' and is definitely a male name. These days, however, people commonly name their girls with boys' names, so it's no wonder everyone is confused.
My uncle’s name was Larkin Eldridge (first and middle). These were family names from my maternal grandfather’s side. They were red-haired Scotch-Irish descendants living in El Paso, Tx around 1905-1980. My uncle was born in El Paso in the mid 1940s. His brothers’ names included Leighton, Douglas, Chadwick, and Owain. As far as I know, his name was always Larkin with no nickname, even though all 5 of his siblings had nicknames, common ones for the time (Dick, Jim, etc).