Let's say we are dealing with an autosomal recessive disease, and 2 heterozygous parents have some children. Of course, the punnet square result is AA Aa Aa aa
I know that the probability of an unaffected child being a carrier is 2/3, BUT what if you are asked the probability that 2 children are BOTH carriers? Do you just multiply 2/3 x 2/3 and get 4/9? I could see this being feasible...but when trying to figure out the chances of EITHER being a carrier wouldn't it be 2/3 + 2/3 = 4/3? 133% chance WTF? What am I missing here?
I know that the probability of an unaffected child being a carrier is 2/3, BUT what if you are asked the probability that 2 children are BOTH carriers? Do you just multiply 2/3 x 2/3 and get 4/9? I could see this being feasible...but when trying to figure out the chances of EITHER being a carrier wouldn't it be 2/3 + 2/3 = 4/3? 133% chance WTF? What am I missing here?