I think you have the question backwards, "Why isn't it possible to have more phenotypes than genotypes?" There are always more or an equal number of genotypes relative to phenotypes. The phenotype for a simple dominant/recessive interaction (for example) T for tall and t for short where TT is tall, Tt is tall and tt is short has three genotypes and two phenotypes. If T and t are co-dominant then TT would be tall, Tt would be intermediate and tt would be short. (Three phenotypes and three genotypes.)
Tall=TT Short=tt
tall; Tt or TT
P1: tt F2: tt
TT or Tt
The genotype of Alice of Hesse is Tt and Leopold is tt.
both must be tt
both must be tt
Either TT or Tt, where T stands for dominant gene for tallness and t for recessive gene.
both must be tt
Firstly, if the condition is recessive, both the man and the child with the condition must have the genotype tt. The mother must have the genotype Tt. This is because if she had TT, all of the children would be Tt and not have the condition. If she were tt, she would have the condition as well. Therefore if the father has tt and the mother has Tt, the other 3 children who do not have the condition must all have the genotype Tt. So: Mother - Tt Father - tt Affected child - tt Other children - Tt
3 : 1 ( since the given situation of segregating genotypes TT Tt Tt tt comes under monohybrid genetic combination, it will show 3 tall plants and 1 dwarf plant because gene T is dominant over t.