引用:
原帖由 mugen-purin 於 2009-5-18 01:45 PM 發表 
i did, but i forgot too
can u explain to me?
If the bad gene is dominant, then your grandma and mom etc will got the sickness. Then you won't probably marry to your cousin as you will have very very very high chance to pass that to your kids
We are talking about the recessive genes
Meaning 1 recessive bad 1 dominant normal gene = normal ( hidden that you don't know )
That makes you possible to marry to someone who looks healthy but their genes may not
for the recessive bad gene makes your kid bad, they must be bad in pair, like MM and Bebe, the twins.
So, both bad genes = 1/8 x 1/8 = 1/64
However, if only 1 bad gene is enough, then chance is 1 - no bad gene at all = 1 - 7/8 7/8 = 1 - 49/64 = 15/64 ~ 1/4
