For a codominant trait, we can take a sample from the population, and count the different genotypes.
| Blood Group (genotype) | M (MM) | MN (MN) | N (NN) | Total |
|---|---|---|---|---|
| Count (percent) | 363 (28.4%) | 634 (49.6%) | 282 (22.0%) | 1279 (100.0%) |
The proportions are our best estimate of the probability that an individual will carry that genotype in the population of London, Oxford and Cambridge. The observed heterozygosity is 49.6%.
We can also make inferences about the population of gametes that gave rise to individuals tested:
| Alleles | M | N | Total |
|---|---|---|---|
| Count (percent) | 1360 (53.2%) | 1198 (46.8%) | 2558 (100.0%) |
The proportions are our best estimate of the probability that a sperm or egg taken from that population will carry that particular allele.