When two individuals with achondroplasia mate, the offspring occur in a ratio of 2 achondroplasia: 1 normal. what is the most likely explanation for these observations?

The achondroplasia is a condition, in which a bone growth disorder cause the condition of disproportionate dwarfism. In humans, this character is inherited as Autosomal dominant trait.

For a person to be normal, the genotype must be homozygous recessive. In case, the person have atleast a single allele for the trait, he or she would be affected.

In this case 2 children are affected, but 1 is normal, which means both the parents are carrier of a recessive allele. Hence, the parents are heterozygous for the trait.

So, it can be concluded that the achondroplasia is an autosomal dominant disease and the individuals in the question are heterozygous.