Question

In people, dimples are a dominantly inherited trait. If both parents are heterozygous for the dimple gene, what is the probability that their child will have dimples?
Responses

25%
25%

50%
50%

75%
75%

100%
100%

Answer 1

To determine the probability that the child will have dimples, we can use a Punnett square to analyze the genotypes of the parents.

Let:
- D = allele for dimples (dominant)
- d = allele for no dimples (recessive)

Both parents are heterozygous, so their genotype is Dd.

Setting up the Punnett square:

```
D | d
-----------------
D | DD | Dd
-----------------
d | Dd | dd
```

From the Punnett square, we get the following genotypes for the offspring:
- DD: 1 (25%)
- Dd: 2 (50%)
- dd: 1 (25%)

The offspring that have at least one dominant allele (D) will have dimples. This includes both the DD and Dd genotypes.

Adding these together:
- DD = 1
- Dd = 2

So the probability of having dimples (DD or Dd) is:
1 (DD) + 2 (Dd) = 3 out of 4, or 75%.

Therefore, the probability that their child will have dimples is **75%**.