Question

Galactosemia is a recessive human disease that is treatable by restricting lactose and glucose in the diet. susan smithers and her husband are both heterozygous for the galactosemia gene. if susan and her husband have four children, what is the probability that: (1 point each)

Answer 1

There are 3 exclusive mutually birth orders that could

make two affecteds and 1 unaffected - unaffected child first born, unaffected child

second born, and unaffected child third born. Thus, there is a 3/64 + 3/64 + 3/64

= 9/64 chance that 2 out of 3 children will be affected.