If three children are born to matthew and jane, what are the chances that the first two children will not express the trait but that the third child will be an achondroplastic dwarf?

The chances are 100 percent for the three children

Explanation:

From the question, it is obvious that both Matthew and Jane are achondroplastic dwarfs. This implies that they are both carriers of the dominant traits. Hence the chances that their third child will be an achondroplastic dwarf is 100 percent because Matthew and Jane both carry dominant genes.