Q. I heard about your new Gender Chromosome Patterns illustration. I can’t find a copy of it and which patterns are for “straight” versus “non-straight” brains?

A. Here is a copy of the PowerPoint® slide that no doubt is a work in progress based on emerging research. Notice that currently there are more options for variations for chromosome patterns that involve a “Y” chromosome.

Notice the two patterns that are marked with an asterisk. This indicates that the SRY gene that triggers testis development is damaged, which can lead to an XY-F (there is a XY combination but the individual appears externally as a female) or that it is copied into the X chromosome, which can lead to an XX-M (the individual appears externally as a male but initial screening only shows a XX combination).

  • For the XXY (47 chromosomes) pattern, estimates are that this occurs in 1/1000 male births.
  • For the XXYY (48 chromosomes) pattern, estimates are that this occurs in 1 in 18,000 – 40,000 male births

As to your last question, this illustrates that people are first and foremost human beings who appear to have chromosomal patterns involving either only X chromosomes or a combination of X and Y chromosomes. As far as is known, none of these patterns differentiate between “straight” and “non-straight” brains.

Here are a few caveats:

  • Human brains are more alike than they are different—there appears to be no gestational “default” position as once believed
  • A person’s “gender” cannot be determined with any certainty by looking at the brain
  • Some individuals have congruent chromosomes, internal sex organs, external genitalia, and personal brain perception about who they are innately, but more are gender non-conforming than previously thought
  • So far, humans who have a “Y” are considered male