My first officer was an old gray haired Bajoran I didn't modify her.
My thirs and fourth officers were alien/trill and they were huge, prolly 6'5" or taller. not sure how the randomizations work for predetermined BO rewards, but I laffed at the randomness, so I didn't modify em.
Well, you gotta remember they are all young ensigns... Military guys know those boots comin out of OCS never looked old enough to cross the street without getting hit by a car, and I am sure that their moms still called them to remind them to eat all of their veggies.....:p
I play as a Female Trill. When I get a female BO I go to Change Outfit and straight away hit "reset". It sets their appearance to be the same as my character. I now have myself and 4 BOs who look exactly like me