Question: Can a person get 2 dominant genes, if so which one comes on top ?

Chris Watt answered on 11 Jun 2020:

Hi Alejandro,

Great question. We normally refer to dominant and recessive versions of genes as ‘alleles’. An allele is a variant of a gene, so you may have dominant and recessive alleles. A classic example is for eye colour, where blue is considered to be a recessive allele and brown is considered to be a dominant allele (it is a bit more complicated than this in reality but lets keep it simple for now!).

And yes, for some genes, people may have what is considered to be 2 ‘dominant’ alleles. This may mean that both ‘come out on top’ which may mean the person expresses a bit of both – like a blend of the two dominant alleles. You may have heard of some diseases being caused by dominant genes – this means that you only need one copy to get the disease. In some cases, people may have 2 dominant disease alleles which sometimes makes the disease more severe, but sometimes may have no difference to just having one copy.

Hope this helps!