Intelligence on the X chromosome

Matt Beckwith (
18 Aug 1996 00:03:07 GMT

catherine yronwode <> wrote:
>John Varela wrote:
>> In <4uu00h$>, Matt Beckwith <> writes:
>> >>It was an incidental issue which arose out of a discussion of the
>> >>ramifications around a recent discovery that a boy's intelligence is
>> >>inherited from his mother, not from his father ... the gene for
>> >>intelligence (but don't ask me to define the term) having now
>> >>apparently been established as being carried on the X chromosome.
>> >
>> >This I find difficult to believe. Perhaps they found a gene on the
>> >X-chromosome which determines IQ to a certain extent. But I bet
>> >there are others on other chromosomes. It just wouldn't make sense
>> >to have a person's intelligence only determined by inheritance from
>> >the mother. And nature usually evolves life forms that make sense.
>> I saw news reports about intelligence being inherited only from the
>> mother. It caused me to wonder how this interacts with the current
>> controversy over whether intelligence can be measured with a single
>> number, such as IQ. If intelligence is found on only one or a few
>> genes, it would seem to support the single-number advocates.
>> I saw no discussion of this question in the press reports, nor did I
>> see any description of how they defined the "intelligence" that is
>> only inherited on the X chromosome. If the definition of intelligence
>> is IQ, and IQ is inherited on only one gene, then to say that
>> "intelligence" is inherited from one gene looks like circular
>> reasoning to me.
>The news ran in the Wall Street Journal, New York Times, etc. At no time
>did anyone (scientists or reporters) claim that there is ONE gene for
>intelligence. At no time did anyone claim that this affects the
>inheritance of intelligence by WOMEN. One research team claims to have
>has identified several genes for intelligence and all are located on the
>X chromosome. Thus men would inherit intelligence from the mother only
>but women could inherit from the mother or father or both.
>This is the sort of information that drives some people into raging
>fury, so i will not defend the issue beyond stating that the research
>was published in a peer-reviewed journal and was thereafter accurately
>reported in the popular press. Accretions of misinformation (the
>reduction to "one gene", the idea that women inherit intelligence from
>their mother only) and arguments over whether IQ itesting is a
>reliable/unreliable measure of intelligence are none pf my business.

Okay, I was inferring something untrue. As a doctor I should know
better. I was thinking that, because the X chromosome is associated with
femininity, intelligence could only be inherited from the mother. But
this isn't true. Both genders have the X chromosome.

What is true about X-linked traits, however, is that, if the trait is a
recessive one, it will show up in all men who have it, and a very small
minority of women who have it (only those women who have the same gene on
both of their X-chromosomes). I doubt that intelligence genes are
recessive genes, but if they are, its presence on the X chromosome would
explain why men are smarter than women (just kidding, just kidding).

FYI, genes which are only inherited from the mother are those which are
on the mitochondrion (a cellular element whose purpose is manufacturing
energy, and which doesn't get sent over to the egg by the sperm during
fertilization). Anybody know which genes these would be?


Matt Beckwith