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A man whose father was colour blind marries a woman who had a colour blind mother and normal father. What percentage of male children of this couple will be colour blind?
A
25%
B
0%
C
50%
D
75%
Detailed Solution
The man gets his Y chromosome from his father, so his X is normal: $XY$.
The woman's mother was colour blind ($X^cX^c$) and her father normal, so she is a carrier: $XX^c$.
Sons get their X from the mother: half receive $X$ and half receive $X^c$, so 50% of the male children will be colour blind.
The woman's mother was colour blind ($X^cX^c$) and her father normal, so she is a carrier: $XX^c$.
Sons get their X from the mother: half receive $X$ and half receive $X^c$, so 50% of the male children will be colour blind.