While doing some follow-up research on this topic I happened upon a very related quote from a MLP fan site:
I hate when people draw anthro or humanized Fluttershy with big breasts. And because this has become a norm to the fandom I instantly look away from any humanized Fluttershy. The “people" with big breasts in the show from the main six would have to be Pinkie Pie, Rarity and Twilight Sparkle. Their life style and personalities fit this as Fluttershy’s don’t.
There is
no explanation as to why they feel that Pinkie, Rarity, or Twilight would be the busty ones nor do they elaborate as to why lifestyle and personalities would fit those sizes. This started me on a parallel track. Do these characters actually have some indications as to what their heights, busts or ethnic background
SHOULD be and not just what fans would like them to have...
To keep things simple I will make the assumption that the character's professions are dictated rather directly by their physique and that there is a high correlation between these aspects and the data about their past and lives from the show creators. (and not from fan fiction or non-cannon sources)
Character - Profession - Other Personality Data Basic IndexApple Jack - Farmer - 2nd Generation Family Farmer, Middle **09** and oldest daughter, Farm is an orchard (vegan/organic), simplistic and stubborn mindset
Flutter Shy - Veterinarian/Animal Care - Sole business owner (remote location), very shy and introverted with low self esteem and/or body issues, has a deep repressed hostility
Pinkie Pie - Baker/Catering - Multi-business owner, extroverted, money focused, youngest daughter of large repressive rural family, nearly manic or hyperactive with addiction tendency and/or OCD
Rainbow Dash - Meteorologist/Athlete (part-time) - Part-time job allows for strong athletic bent, very competitive, judgmental and aggressive, masculine mannerisms, implied lesbianism
Rarity - Seamstress/Fashion Designer - Business owner, extroverted and perfectionist, appearance motivated and superficial, implication of being older or more mature than others, oddly self-deprecating and giving at times (guilt or failure issues).
Twilight Sparkle - Royal Princess - Heredity and heraldic based position, sheltered and reserved but with knowledge based assertions, Student-Librarian-Teacher background, rule based approach to life, weaker social skills.
From this I would make the following suggestions to height / bust / ethnicityApple JackHeight - medium
Bust - medium small (A or B)
Ethnicity - Austrian or Southern Germany
Strenuous farm labor on a vegan diet describes a lean body from a culture used to apple orchard farming which suggests northern climate continental origins. Overly short or tall frames are not conducive and multiple generations suggests that morphology would have stabilized to a mid-line Germanic height.Flutter ShyHeight - tall
Bust - large to very large (F or G)
Ethnicity - Nordic/British Isles
Deep body image issues and extreme introversion would suggest early body ridicule and early unique physical features. This coupled with skin and eye coloring point to a tall thin but busty frame from northern Europe. Remote animal business location supports a familiarity to Nordic social conditions.Pinkie PieHeight - medium tall
Bust - medium large (D or E)
Ethnicity - Irish/British Isles
Strong extroversion and hard focused work effort in a bakery with an implied harsh agrarian "rock farm" youth with possible nutritional deficiencies coupled with the eye and hair color strongly point to Irish background. Malnutrition in youth (and being youngest and thus oldest gametes) point to neurological and behavior issues. General build would be strong, slightly stocky but rounded as per British Isles norm.Rainbow DashHeight - short
Bust - very small (AA or A)
Ethnicity - Hispanic
Excessive athletic fixation and overly competitive extroverted actions meld well with a compensating behavior for lack of overly famine features and stature especially in light of the implied lesbian tendencies all of which could come from a youth in a more chauvinistic culture. Lack of a full-time job (one that is shared with others doing the same role) points to an internal conflict with cultural norms and gender roles.RarityHeight - medium tall
Bust - medium (C or D)
Ethnicity - Italian/Japanese mix
A background from cultures with a high fixation on appearance, arts, fashion, etc. but just lacking the physical ideal (being a little too short and a little too busty) needed to actually accomplish a career as a model there would be a move to produce the works and move just outside the focus or live through others while still yearning for acceptance.Twilight SparkleHeight - medium
Bust - medium large (D or E)
Ethnicity - Asian Indian (high caste mother) with British landed aristocrat father
Due to the burdens of a very regimented and prescribed youth and the focus on title, standing, and merit based on birth the yearning for normal social interaction would be along channels provided by others in control, such as boarding/prep school and books and not normal interaction. The burden to try and mesh cultural pressures and family or peerage history of repression would cause a focus/reliance on impersonal and detached rules of conduct and proper decorum while remaining social naive.