Question

A man with a widow’s peak, who inherited it from his mother since his father does not have one, has children with a woman who has a straight hairline. What would be the phenotypic ratio of their children?
1:1
1:2:1
3:1
4:1

Answer 1

A widow's peak is typically considered a dominant trait (let's represent it as "W"), while a straight hairline is a recessive trait (represented as "w"). Since the man has a widow's peak and inherited it from his mother, he must have at least one dominant allele (W). Given that his father does not have a widow's peak, we can conclude that the man has the genotype Ww (heterozygous) for the dominant trait.

The woman has a straight hairline, which we can represent with the genotype ww (homozygous recessive).

When we cross these genotypes (Ww x ww), we can use a Punnett square to determine the possible genotypes of their children:

```
W | w
----------------
w | Ww | ww
----------------
w | Ww | ww
```

From this Punnett square, we see the potential genotypes of the children:

- 50% Ww (widow's peak)
- 50% ww (straight hairline)

This results in a phenotypic ratio of:

1 (widow's peak) : 1 (straight hairline), or simply written as 1:1.

Therefore, the correct answer is **1:1**.