Question

A study found that children with light-coloured eyes are likely to have parents with light-coloured eyes. On this basis, can we say anything about whether the light eye colour trait is dominant or recessive? Why or why not?

Answer 1

Let us assume that children with light-coloured eyes can either have LL or Ll or ll genotype. If the children have LL genotype, then their parents will also be of LL genotype.
LL × LL
$\downarrow$
LL
If the children with light-coloured eyes have ll genotype, then their parents will also have ll genotype.
ll×ll
$\downarrow$
ll
Therefore, it cannot be concluded whether light eye colour is dominant or recessive.