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?

Explanation

No. It is not possible to arrive at any such conclusion, If we assume that light colour eye is a dominant trait, then children with light-coloured eyes are likely to have
•Both the parent with light coloured eye (homozygous or heterozygous-LL/LI)
• One of the parent is light coloured (homozygous -LL or heterozygous-LI) and the other is not (II).
If we assume that light colour eye is a recessive trait, then children with light-coloured eyes are likely to have
• Both the parents with light coloured eye (homozygous recessive II)
  • Neither of the parents has light coloured eye (heterozygous dominant -LI)
• One parent has light coloured eye (II) while the other does not have (heterozygous dominant LI)
  Since two copies of traits are inherited from parents, one from the mother and the other from the father, unless we know the nature of these two variants of traits we cannot tell which is dominant and which is recessive. Hence the information given in the statement is insufficient to conclude the traits of the parents.