Genetics quick q

[mg777]

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A woman carries a sex linked lethal gene that causes spontaneous abortions. She has 6 kids. How many of her kids do u expect to be boys?

0
1
2
3
4

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topscore says the answer is 2.

I figure to do a punnet sqare(Below), which shows half of her male sons would die. So if she has 6 kids, 3 would be assumed to be male, and out of those 3, half would die. So it seems like the answer could be 1 or 2. whats the deal?

X Y
X (Lethal) X (Lethal)X X(Leth.) Y
X XX XY

 

[sinned]

Let me try, since one of the women's X chromosomes carries the lethal gene, she will have offsprings as such, XX, X*X, XY, X*Y, so the probability of having a lethal son, is 1 out of 4 children...so if she has 6 children, the possibility of having a lethal son is 6/4 = 1.5 since you can't have half a child, I assume you round up to get a number of 2, but I doubt the DAT will give you questions like this...

 

[Typo]

My guess: Since she's a carrier for the sex-linked gene, there's a 50% chance that her boys will get it. Since there's also a 50% chance that she'll have a boy rather than a girl, that makes a 25% chance that she will have a spontaneous abortion. So, with 6 kids, we can speculate that she has had 2 spontaneous abortions. Having been pregnant 8 times, she will have had 4 boys and 4 girls, but 2 of those boys will have been aborted and 2 will have survived.