a man with blue eye married a girl with broun eye and the mother of the girl has blue eye. What is the probability that their children will have blue eye

1 answer

It has been taught to millions of high school students that it is two genes, nowadays, a few teachers (I hope yours) is teaching that eye color is much more complicated, and two genes are required:
http://genetics.thetech.org/sites/default/files/EyeColorChart2.gif

the man obviously is bb bb.
The wife can be to have brown eyes
BB GG
BB Gb
BB bb
Bb GC
Bb bb

but the mom of the girl was blue eyed, so she was bb bb.
which tells me then the wife with brown eyes, has to be Bb bb or BB bb.

if this wife and the man has kids, then we are crossing bb bb X Bb bb (or BB bb)
in case Dad is Bb bb, then the kids can be bb bb or Bb bb . You can pundett those possibilites out. IF the man is BB bb, then the children must be Bb bb, all brown eyed. so blue eyed kids vs brown eyed: 50:50 chance. Pundett them out.

http://genetics.thetech.org/how-blue-eyed-parents-can-have-brown-eyed-children