title: Determinants of breast appearance and aging in identical twins.
abstract: BACKGROUND
  Appearance, aging, and disorders of the breast are multifactorial. There are intrinsic, patient-specific characteristics, such as breast growth during puberty and propensity for breast cancer, which are primarily inherited. There are also environmental factors, which can be potentially controlled. Monozygotic twins provide an excellent research opportunity to examine the role of extrinsic factors in subjects with identical genetic predispositions.
  
  
  OBJECTIVE
  The authors investigate the role and significance of various environmental and acquired factors on breast aesthetics.
  
  
  METHODS
  Identical female twins were recruited during the Twins Days Festival in Twinsburg, Ohio, in 2009 and 2010. After consent was obtained, enrolled subjects completed a comprehensive survey on their medical and personal history. Standardized digital photographs were taken by medical photographers. Sixteen aesthetic breast features were subjectively rated by 6 plastic surgery residents blinded to the survey results. These ratings were then analyzed against survey data to determine the significance of different exogenous factors on breast appearance.
  
  
  RESULTS
  A total of 161 pairs of identical female twins (n = 322) with a mean (SD) age of 47.6 (14.5) years were recruited. Twins who moisturized their skin daily had significantly fewer rhytids (P = .002). Twins who received hormone replacement therapy after menopause had more attractive breast shape, size, projection, areolar shape, and areolar size (P < .03). However, twins who had a higher body mass index, greater number of pregnancies, and larger cup sizes had significantly less attractive breasts (P < .05). Twins who smoked cigarettes and consumed alcohol also had significantly less attractive breasts (P < .05). Twins who breastfed had less attractive areolar size and shape but better skin quality than their counterparts who never breastfed (P < .03). Finally, there was a significantly higher incidence of breast pain in twins who primarily slept on their sides compared with twins who primarily slept on their backs (P < .008).
  
  
  CONCLUSIONS
  This study implicates several environmental factors that significantly affect the aesthetic quality of breasts.
authors.affiliation: Department of Plastic Surgery, University Hospitals Case Medical Center, Cleveland, Ohio, USA. Hooman.Soltanian@UHHospitals.org
authors.forename: Hooman T
authors.initials: HT
authors.lastname: Soltanian
authors.forename: Mengyuan T
authors.initials: MT
authors.lastname: Liu
authors.forename: Adam D
authors.initials: AD
authors.lastname: Cash
authors.forename: Rodrigo A
authors.initials: RA
authors.lastname: Iglesias
mesh_terms: D000328:Adult; D000368:Aged; D000375:Aging; D000428:Alcohol Drinking / Q000453:epidemiology; D015992:Body Mass Index; D001940:Breast / Q000033:anatomy & histology*; D001942:Breast Feeding; D005260:Female; D020249:Hormone Replacement Therapy / Q000379:methods; D006801:Humans; D008875:Middle Aged; D010781:Photography; D017698:Postmenopause; D017584:Reproductive History; D016037:Single-Blind Method; D012907:Smoking / Q000009:adverse effects; D014430:Twins, Monozygotic