Xét riêng từng cặp gen:
-Cặp $\frac{{AB}}{{ab}}$
$P$: $\frac{{AB}}{{ab}}$ × $\frac{{AB}}{{ab}}$
$G_{F1}:$ AB,ab AB,ab
$F1:$ $1\frac{{AB}}{{AB}}:2\frac{{AB}}{{ab}}:1\frac{{ab}}{{ab}}$
→$F1:3A-B-:1aabb$
-$Dd×Dd$ →$F1:1DD:2Dd:1dd$ (KH: $3D-:1dd$)
-$Hh×Hh$ →$F1:1HH:2Hh:1hh$ (KH:$3H-:1hh$)
-Tỉ lệ KH mang $3$ trội $1$ lặn :
+$A-B-D-hh$: \(\frac{3}{4} \times \frac{3}{4} \times \frac{1}{4} = \frac{9}{{64}}\)
+$A-B-ddH-$:\(\frac{3}{4} \times \frac{3}{4} \times \frac{1}{4} = \frac{9}{{64}}\)
⇒Tỉ lệ KH mang $3$ trội $1$ lặn : \(\frac{9}{{64}} + \frac{9}{{64}} = \frac{9}{{32}}\)
