Which is most likely explanation for a child exhibiting a heritable trait that nerthier parent exhibits?

Question

A grandparent exhibits the trait, and the child inhertrited it directly from that person

The trait is recessive, and the child inherited a recessive allele from each parent.

A mutation occured and the child echibits a new trait due to the mutation

Answer 1

The most likely explanation for a child exhibiting a heritable trait that neither parent exhibits is:

The trait is recessive, and the child inherited a recessive allele from each parent.

In this scenario, both parents can be carriers of the recessive allele (they have one dominant allele and one recessive allele, leading to them not expressing the trait), and if the child inherits the recessive allele from both parents, the child will express the recessive trait.

While a mutation could also result in a new trait, such occurrences are generally less common than inheriting a recessive trait. The situation with a grandparent exhibiting the trait is also possible, but it does not explain the direct inheritance when considering the immediate parents' genetic contributions.