Question

When two average-height parents give birth to a child exhibiting achondroplasia, it is most likely due to a new mutation. this is because __________?

Answer 1

The question already suggests the answer: if the child has a genetic disease that both parents don't, there are only two possibilities:

- the gene is recessive and both of the parents are carriers, but since they only have one of the genes, it doesn't manifest for them

- the gene is dominant - but then one of the parents (or both) would have it too - so it must be a new mutation

answer: it's caused by a dominant gene