[Paul C. Jesup]

Women can possess both opsin pigments because they have two X chromosomes.

I guess the people who did this study do not understand one very interesting genetic fact about women. One of the two X chromosomes in women is TURNED OFF, cases where both X chromosomes are turned on leads some serious birth defects.

[uncleshag]

Knew...ahem... an exotic dancer named DoubleXX Candy near Ft. Jackson in the 70's.

You just explained it all to me.

She had two serious birth defects.

She could see red though (and green, of course!)

[Diddle E. Squat]

Is it true that the only trait carried on the Y chromosome is hairy earlobes?

[Doctor Stochastic]

I thought the turning off of one of the X-chromosomes occurred on a cell-by-cell basis leading to mosaicking in case of heterozygous sex-linked traits.