If you are a woman and have ever felt that nature has perhaps
not been impartial in giving you a fair share of faculties, look no
further.
As the work of Dr Valerie J Grant, an evolutionary psychologist at
The University of Auckland in New Zealand, has determined, there is
strong evidence to suggest that the sex of a newborn is determined in
large part by the personality traits and hormonal profile of the mother.
In a paper that has given her worldwide renown, Sex determination and
the maternal dominance hypothesis, Dr Grant explains how.
The maternal dominance hypothesis
On the basis of the results coming from a series of studies carried
out over a 30-year period, various social scientists have identified
‘consistent, statistically significant evidence’ to support the view
that there is a “maternal involvement in the predetermination of the sex
of her infant.”
What is this maternal involvement?
As incredible as it sounds, the maternal involvement at hand is that
women with dominant personality types have consistently been found to be
as much as 80% more likely to give birth to sons.
How come?
• Dominance is a personality trait in humans that is characterised by
sub-traits such as being “influential, ascendant, prevailing,
authoritative or high-in-control.” In their entirety, a dominant person
is an individual who can be found “acting overtly so as to change the
views or actions of another.”
• As such, dominance in humans is underpinned by the hormone
testosterone, with a high correlation between scoring high on dominance
personality tests or other markers and serum (blood) testosterone
levels.
• The sex of an infant is determined by whether, at the time of
conception, the woman’s eggs are fertilised by a sperm bearing an ‘X’
(female) or ‘Y’ (male) chromosome. According to Dr Grant, high
testosterone levels at this time in the woman will prime her to be
receptive to the latter (Y chromosome) and lead to the development of a
male infant.
• In her paper Dr Grant identifies: A meta-analysis of all studies
showed that women who later bore sons were significantly more likely to
have scored higher on the tests of dominance than those who later bore
daughters.
But that’s just the half of it. Dr Grant refreshes the maternal
dominance hypothesis with studies showing that personality traits and an
individual’s hormonal profile are rooted in a ‘complex two-way
interaction between biological as well as environmental influences.’ In
other words, any changes in an individual’s status-quo that is tied to
dominant behaviour is likely to be accompanied with changes in
testosterone levels. Think of a divorced, single-mother previously
working to raise several children, now getting married to a wealthy and
protective man. According to Grant’s work, with the ceasing of
dominant-status their would likely be a decline in its hormonal basis
(testosterone.)
