ATYPICAL GENDER DEVELOPMENT (GENDER DYSPHORIA): BIOLOGICAL EXPLANATIONS Flashcards
Biological explanations
GID excludes intersex conditions that have a recognised biological basis, however GID may be plausible that GID may be subject to some biological influence
Brain sex theory
Suggest that GID is caused by specific brain structures that are incompatible with a persons biological sex
Attention has been paid to those areas of the brain that are dimorphic (take different form in males and females)
Ning Zhou et al
studied the bed nucleus of the stria terminals which is assumed to be fully developed at age 5 and around 40% larger in males than females In post-mortem studies of 6 male-female transgender individuals, the BSTc was found to be a similar size to that of a typical female brain
Kruijver et al
who studied the same brain tissue but focussed on the number of neurons in the BSTc rather than the number confirmed this in a follow up stud. Again the 6 transgender individuals showed a sex-reversed identity pattern with an average BSTc neuron number in the female range
Genetic factors
Evidence suggests that GID may have a genetic basis
Coolidge et al
assessed 157 twin pairs (96 MZ, 61 DZ) for evidence of GID using a clinical diagnosis The prevalence of GID was estimated to by 2.3% with 62% of these cases said to e accounted for by genetic variance. This suggests there is a heritable component of GID
Heylens et al
compared 23 MZ twins with 21 DZ twins where one of each pair was diagnosed with GID
They found that 9 (39%) of the MZ twins were concordant for GID compared to non of the DZs which would indicate a role for genetic factors in the development of GID
Twin studies are inconclusive
Although evidence form twin studies that GID may be partly explained by hereditary findings are inconclusive, the twin studies don’t have very high concordance rates, it is also very difficult to separate the influence of nature and nurture within these investigations. Twins especially MZ may influence each other, and the environmental conditions they are exposed to are likely to be very similar, also due to the fact that GID occurs so rarely sample sizes in twin studies tend to be small limiting the extent to which effective generalisations can be made
Biological explanations oversimplify a complex concept
Biological explanations are often criticised for their tendency to reduce complex condition and behaviours to simple genetic, neuroanatomical and or hormonal level. The danger here is that other contributory factors occurring at higher psychological or social levels may be obscured or ignored. An integrationist combination of several different levels of explanation may be especially relevant in the case of GID, a complex condition that is unlikely to be explained by a single influence
Contradictory evidence of BSTc
Its claimed that the BSTc is fully formed at age 5 so any hormone treatment that trans individuals may undergo as part of gender reassignment should not have a bearing on the BSTc. This assumption has been challenged by Hulshoff Pol et al who found that trans hormone therapy did affect the sixe of the BSTc. Therefore observed differences in the BSTc may be due to hormone therapy rather than being a cause of GID
Chung et al (contradictory evidence)
claim that pre-natal hormonal influences are not triggered until adult hood. So although the hormonal influences occur before birth, the structural changes in the brain that are the results of these don’t occur until much later. This casts doubt on the idea that dimorphic brain differences
are present in early childhood
