I don't think it is weird. My sister and I grew up without nicknames, but my brother (Gordon) has always gone by Gordie (when he was a kid) or Gord (teen/adult). He only uses his full name in professional settings, and it would never occur to me to call him Gordon.
Likewise, MH is Joshua, but is frequently called Josh. His brother, Andrew, has always been called Andrew, not Andy or Drew.