Twin Research and Human Genetics

Articles

Body Mass Index and Breast Size in Women: Same or Different Genes?

Tracey D. Wadea1 c1, Gu Zhua2 and Nicholas G. Martina3

a1 School of Psychology, Flinders University, Australia. tracey.wade@flinders.edu.au

a2 Queensland Institute of Medical Research, University of Queensland, Australia.

a3 Queensland Institute of Medical Research, University of Queensland, Australia.

Abstract

The objective of the current study was to investigate the heritability of breast size and the degree to which this heritability is shared with BMI. In a sample of 1010 females twins (mean age 35 years; SD = 2.1; range 28–40), self-report data pertaining to bra cup size and body mass index (BMI) was collected in the context of self-report data and an interview relating to disordered eating respectively. In a sample of 348 complete twin pairs who completed data collection (226 MZ pairs and 122 DZ pairs and 360 incomplete pairs (170 MZ and 190 DZ)), we found that the heritability of bra cup size was 56%. Of this genetic variance, one third is in common with genes influencing body mass index, and two thirds (41% of total variance) is unique to breast size, with some directional evidence of non-additive genetic variation. The implications of these findings with respect to previous research linking breast size with reproductive potential are discussed.

(Received June 16 2010)

(Accepted July 29 2010)

Keywords

  • breast size;
  • body mass index;
  • heritability;
  • bivariate Cholesky

Correspondence:

c1 Address for correspondence: Professor Tracey Wade, School of Psychology, Flinders University, PO Box 2100, Adelaide, SA, 5001, Australia.

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