It isn't about height, it is about frailty. Something about their bone structure. Imperials are shorter than Nords, but don't seem like wimps. The Bretons all look like scrawny weasels playing magic at a LARP festival.
Maybe your game's slider is glitched. Because my male Bretons have 2 tickets to the same gun show...
Breton...http://cloud.steampowered.com/ugc/937004266022355621/DD531E53CF2AD3A216153AFD6AE4D40349877184/
Imperial...http://cloud.steampowered.com/ugc/937004266022351701/EAF5E4B3BD61C2C62BFD8898343F911669211C12/
Nord...http://cloud.steampowered.com/ugc/937004266022346856/07EC148A962C83F51A921368B137BCB474DCEDE2/