[Avodah] God who knows the future

[Joel C. Salomon]

On 08/16/2011 10:09 AM, T613K at aol.com wrote:
> I also heard or read somewhere that because Dina was supposed to be a
> boy and changed to a girl, she was infertile.  (Which I realize
> contradicts a midrash that she did have a child, "Shaul ben haCanaanis.")

Some months ago I read an article (I don’t remember where; one of the YU
journals, perhaps?) that suggests a mechanism for the gender-switch:

It seems that while women have two X chromosomes, only one is active in
any given cell.  The choice of which one is active happens when the
embryo has only a small number of cells (on the order of 8 or 16, IIRC).
 In each cell, one X chromosome turns off, and stays off in all that
cell’s descendants.  See <http://en.wikipedia.org/wiki/X-inactivation>.

In some rare cases, an X and Y chromosome can be fused.  If the sperm
cell carries such an X+Y chromosome (it normally has only one of X or
Y), then the child will be XXY, which usually yields an infertile male.
 At the time the X chromosomes turn off, in approximately half the cells
it will be the X+Y fusion and in the rest the X solo that stays active.

But — if by some improbable chance (1:2^16), or by miracle, *all* of the
X+Y fusions are deactivated, then the child will be a *fertile* female.

--Chesky