Predicting Deafness Of Children Based On Genes

[Tudor101]

I was given a scenario in which a woman is heterozygous for the deafness gene, her husband also being heterozygous. I was asked to complete a punnett square, in which I used D for the deafness gene and d for the hearing gene, and I got DD, Dd, Dd and dd, so from that I figured that there's a 75% chance of carrying the deafness gene, 25% of the child being deaf and 25% of the child being able to hear.

Assuming the woman had another child, I was supposed to give the probability of her having two deaf children in a row, and I thought that would still be 25%, thought something tells me I am extremely wrong.

Finally, I'm supposed to give the probability of the woman having 3 deaf children in a row and to explain why that is. I'm a bit stuck on the probability bits, my apologies if this is a dumb question to ask.

[bednobs]

i'm not sure your original assumptions hold up. if there's a 25% chance of a child being deaf, there cant also be a 25% chance that the child will be hearing.

[bednobs]

i didnt make that clear - what i mean is tat your figures don't add up to 100% in the case of deafness or not which the should do.

[woofgang]

so DD=deaf and gene carrier
Dd=hearing and gene carrier
dD=hearing and gene carrier
dd=hearing and not gene carrier

Is this right....in this case yes 75% chance of hearing, 25% chance of being deaf =100%
The other (carrier calculation) is the same numbers 75% of being carrier, 25% chance of being not a carrier=100%

There are (as I understand it) two arguments about the second and third children. One is that the odds reset with every child so every child has the same 25% chance of being deaf BUT there is the goat and car scenario which I know about but don't understand which says that the odds change.
https://betterexplained.com/articles/understanding-the-monty-hall-problem/