Answer:
2 out of 4
Explanation:
Let the allele for cleft chin be represented by A, while the alternate recessive version would be a.
A parent that is heterozygous for cleft chin would have the genotype Aa.
A parent without cleft chin would have the genotype aa.
Aa x aa
Aa Aa aa aa
Aa - cleft chinned = 2/4
aa - normal chin = 2/4
Thus, two out of every four (2/4) of their offspring would have cleft chin.
