Infer the number of genes in the ancestral states

Question

[Cacau]

I have three species A, B and C and their phylogenetic relationships as (A, (B, C));

I also have the gene pool of each species: gene1, gene2 and gene3 for species A, gene1 and gene2 for species B; gene2 and gene3 for species C.

Now what I am going to do is to infer the number of each gene in the ancestral states (e.g. in the last common ancestor of species B and species C and also the last common ancestor of all of these three species). I want to make the following figure

.

How should I do it?

[anp375]

What's the "number of each gene"?