Answer:
Sample size of offspring is too small and we can't make assumptions based on phenotype analogy about how many will have a cleft chin. But we can say with certainty that each kid has a 50% chance to have a cleft chin.
By phenotype analogy though, out of 4 children 2 would have a cleft chin *logically*
Step-by-step explanation:
Genotypes of people that have a phenotype of a cleft chin: Cc , CC
Genotypes of people that have a phenotype of no cleft chin : cc
The first rule of Mendel applies where during myosis there is the independent share of chromosomes in the gametes and the independent combination between spermatozoa and ovums
First we do the recombination of the mother and father:
Parents: cc (x) Cc
Gametes: c / C, c
Offspring: Cc , cc
Phenotype analogy : 50% Cleft chin : 50% No cleft chin
For each child bearing the chance to be born with a cleft chin or not is separate and one birth doesn't influence another. The analogies in phenotypes come from statistics with large numbers of offspring , in which four children is a very small number. So I would have to say that each child has a 50% chance to be born with a cleft chin.
Now if they consider this sample size satisfactory (which I don't think so) then 2 kids would *logically* have a cleft chin. But I stand with the thought that the sample size is too small for the phenotype analogy to be representative of reality and the correct answer is that we can't tell.
Hope this helps.