Bio question

[UnimaasMED]

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A woman carries a sex-linked lethal gene that causes spontaneous abortions. She has six children. How many of her children would you expect to be boys?


Can somebody please explain. I don't get the explanation in topscore (the part which says making a Punnett Square reveals 8 offsprings?. I get 4.😕)

 

[Troyvdg]

A woman carries a sex-linked lethal gene that causes spontaneous abortions. She has six children. How many of her children would you expect to be boys?


Can somebody please explain. I don't get the explanation in topscore (the part which says making a Punnett Square reveals 8 offsprings?. I get 4.😕)

I'm confused on the explanation topscore gave. How could 8 offspring be boys if she only had 6 children?

 

[gigawatt]

The mom is XX and the dad is XY, where X is the lethal allele. I can't format the Punnett square here, but you can follow that there would be four possible zygotes formed:

XX: daughter survives, is not a carrier
XY: son survives
XX: daughter survives, is a carrier
XY: son is aborted

So for every three kids that are born, you expect one to have been aborted. For six kids, you'd expect 4 daughters and 2 sons (the other 2 sons were aborted).