Berni Ryan (Krystal Cave) and Patrick Ryan (Kale Brock) were originally supposed to be Irish immigrants and the metaphorical "hand grenade" was the visit to Australia from their parents who were not aware they were gay.
The original character name of Dr Dean Campbell (Aaron Broomhall) was Gene and was derived from the core production team's obsession with Star Trek (1966). Gene Roddenberry was the creator of Star Trek (1966), however there was concern that a non-American audience would be confused by it sounding as if he were called "Jean".