Given your knowledge about genetics and heredity, answer the following question about color-blindness.

Question

A woman gives birth to a set of fraternal twins: a girl and a boy. She also passes on a color-blindness gene. Which of the children is more likely to be color-blind?
(1 point)
Responses

the girl is more likely to be color-blind from birth
the girl is more likely to be color-blind from birth

the boy is more likely to be color-blind from birth
the boy is more likely to be color-blind from birth

the girl will never be color-blind because the gene came from her mother
the girl will never be color-blind because the gene came from her mother

the boy will never be color-blind because the gene came from his mother
the boy will never be color-blind because the gene came from his mother

Answer 1

Color blindness is typically a sex-linked trait that is associated with the X chromosome. Since males have one X and one Y chromosome (XY) and females have two X chromosomes (XX), the inheritance pattern of color blindness is different for boys and girls.

If a woman carries the gene for color blindness on one of her X chromosomes, she can pass that gene to her children. The possible scenarios for the girl and boy are as follows:

• The boy (with one X chromosome from his mother) has a 50% chance of inheriting the X chromosome that carries the color blindness gene. If he inherits that X chromosome, he will be color-blind.
• The girl (with two X chromosomes) could inherit one normal X chromosome and one X chromosome with the color blindness gene. If she inherits one normal X chromosome from her father (who has a normal vision since males inherit only one X), she will be a carrier but not color-blind. She would need to inherit two X chromosomes carrying the color blindness gene (one from each parent) to actually be color-blind, which is less likely.

Therefore, the boy is more likely to be color-blind from birth, because he only needs one affected X chromosome to express the trait.

The correct answer is: the boy is more likely to be color-blind from birth.